Brent crude has just hit $100 a barrel for the first time since 24 July, as military strikes in the Middle East escalate.

Brent crude, the global oil benchmark, jumped to $100.19 a barrel, up more than $2, and a 2.2% increase. The oil price has risen by a quarter since early last month as hopes vanish for a deal between the US and Iran to end the six-month war that began with air strikes by the US and Israel on Tehran on 28 February.

This week, attacks by Iran-backed Houthi rebels from Yemen have set Saudi oil facilities ablaze, in an escalation of the conflict. The attacks could threaten oil shipments via the Red Sea, an alernative route to the strait of Hormuz which has been effectively closed for months.

The boss of National Air Traffic Services, which is half-owned by the government, has insisted that the organisation has invested enough in its systems.

told BBC Radio 4's Today programme:

Nats was actually a partial privatisation, 25 years ago, and since that point has had access to funding, we've invested way more than a billion [pounds], in technology over that time. Our service has consistently improved. Our safety has consistently improved from a very good base. But all of those things don't detract from the fact that when these things happen, it is disappointing and upsetting, for which I apologise.

We are in a critical national infrastructure business where safety is our priority and it runs 24/7. It runs, you know, every single day of the year, every minute of the day, every minute of the night. It is never quiet in UK skies. Inevitably, things do go wrong in complex systems. We never want them to. We always hope they won't, but we absolutely plan for them to and make sure we handle them properly.

When asked if they "go as wrong in other countries", Rolfe replied:

Absolutely. In fact, I would say the UK has one of the best reputations in the world for its air traffic control service, both from a safety perspective and from a resilience perspective.

We do have one of the best systems and one of the best services in the world. and that's consistently recognised globally.

The UK cannot have a repeat of the travel disruption seen at airports, the foreign secretary has said.

Asked about the flight chaos, told BBC Breakfast:

First of all, I want to apologise to all of the passengers who have faced disruption.

This is frankly unacceptable. It was a problem at the National Air Traffic Service, but we can't have this happen again.

The transport secretary, , is calling in the head of the National Air Traffic Service this morning to get answers to this. Miliband added:

Frankly, we've got to have our airports running smoothly and properly, without those problems, and that is what the transport secretary will be asking for from the head of the National Air Traffic Service.

The boss of , , has ruled out a cyber attack as a cause of the flight chaos, and apologised to passengers caught up in the flight chaos caused by a system issue on Tuesday, and said he understands their frustration –- but stressed that safety comes first.

Speaking to BBC radio 4's Today programme, he said:

I'd like to start, as you might expect, by apologising to everyone who's been impacted by the issue that we had yesterday.

In terms of the recovery, I absolutely understand the frustration. There is nothing we hate more than delaying people, and not allowing them to get to their destination. It disrupts airports and disrupts airlines. And we absolutely take accountability and responsibility for that. That is our job. But our job is also to make sure that people stay safe. We never do this lightly.

He ruled out a cyber attack.

We will be doing a very, very thorough and full investigation. We have at this point ruled out cyber. We don't believe it was a cyber attack.

Obviously my focus and that of the team has been on both getting our system operating back up normally, which it is now. But there's obviously a huge tail to the disruption. And we'll be working on that through the course of today.

And then obviously our attention will turn to exactly what's happened, this particular incident. What I will say is I don't believe we've ever seen an incident happen more than once. So this will be something different that we've never seen in 50 years of operation.

Rolfe insisted that Nats dealt with the issue as quickly as it could:

We had everybody on site. Everybody was in the right place. We had all the engineers in place. We had our various partners from software industries and so on, all on hand. So this was resolved as quickly as it could bebut within the limits of making sure that it all stayed safe.

In the markets, oil prices are rising towards the $100 a barrel level for the first time since July.

Brent crude has jumped 1.5% to $99.36 a barrel, as escalating attacks across the Middle East are fuelling fears over supply disruptions.

Iranian-backed Houthis in Yemen launched strikes on several Saudi cities while US forces hit several Iranian oil tankers and Iran targeted a US base in Jordan and attacked ships.

There is some confusion over the situation at airport.

Heathrow said on X this morning:

Following yesterday's technical issue, flights are operating today, but some disruption may continue as airlines reposition aircraft and crew. Please check your flight status with your airline before travelling to the airport and only travel if your flight is confirmed to be operating.

We apologise to those affected and have extra colleagues across our terminals to support passengers while we work with NATS and airline partners to restore normal operations as quickly as possible.

However, the flight tracking website Flightradar24 says 177 flights have been cancelled so far on Wednesday, nearly all at London-Heathrow.

Good morning, and welcome to our rolling coverage of business, the financial markets and the world economy.

The boss of the air traffic control provider Nats has been summoned by the UK transport secretary, as flight chaos carried on into a second day after a system issue, with after more than 1,300 flights cancelled to and from UK airports.

provides air traffic control services to 15 UK airports. Its chief executive is due to speak to , before she addresses MPs in the Commons for the second reading of the Civil Aviation Bill.

Tens of thousands of passengers have been caught up in the chaos, with more cancellations and delays expected as airlines deal with the knock-on effects at airports including Heathrow, Gatwick, Manchester and Stansted.

According to FlightRadar, 246 flights had been cancelled at Heathrow Airport by 6am on Wednesday, while Gatwick passengers faced 33 cancellations.

Rolfe said he "always accept(s) full responsibility" when asked if he was considering his position after the incident.

He told Sky News:

I am the CEO of a piece of critical infrastructure, so it is my job to take responsibility for that.

What I absolutely take responsibility for is keeping people safe and delivering the best service we possibly can on a day like today.

You will understand my focus is entirely about how we actually resolve this issue, get things back to normal, help our airlines, our airport customers and the travelling public.

The "technical issue" at the air traffic control services provider Nats caused Britain's third major stoppage in just over three years. Nats said on Tuesday evening:

This has been a very complex recovery and has created difficulties for the whole aviation network, from which it will take time to recover.

The breakdown started at about 1pm on Tuesday and affected departing flights at many of Britain's biggest airports including Heathrow, Gatwick, Manchester and Stansted. By the time Nats said it had fixed its flight processing system almost four hours later, most flights scheduled to depart were yet to take off. The disruption spread to include incoming flights to much of southern England.