The transport secretary has confirmed that a computer failure at the West Drayton air traffic control centre was the reason for widespread delays throughout the UK's airport network.

Passengers faced delays of around two hours following the systems problem.

Thousands of passengers were left grounded when a computer upgrade went wrong.

The problem hit the first 90 minutes of flights out of the UK and was resolved shortly after 7.00am.

Speaking to the BBC on Thursday, Darling denied that government under-investment in air traffic control was to blame for the problem.

"The air traffic control system in this country is very good compared with other countries," he said.

"We are putting the money in, it is making a difference. If you look at the delays caused by air traffic control failure they have come down dramatically over the last few years.

"It is very very unfortunate and extremely irritating if you happen to be flying today that during the course of testing for an upgrade and improvement to the West Drayton system something went wrong and as a result you have got this disruption."

A spokesman for the air traffic control service said passenger safety was not put at risk as a result of the systems failure.