Thousands of air passengers were facing travel misery last night after an air traffic computer problem triggered mass flight delays and cancellations.

Travellers throughout the country were left waiting for up to six hours for flights after a software problem forced air traffic controllers to halve the number of aircraft in the skies.

The problem at the £623m National Air Traffic Services (Nats) centre in Swanwick, Hampshire, was discovered at 6.30 am yesterday and took more than five hours to rectify.

Business and holiday flights at the region's main two airports were severely affected.

Thirteen flights into Newcastle were delayed by up to five hours, which had a knock-on effect on departures, while five flights from the North-East's main airport were cancelled altogether.

Passengers were further delayed by a separate problem in the afternoon which occurred with an air traffic system in Brussels used to direct planes in Europe.

This meant all flights leaving Newcastle faced some disruption throughout the day.

On Teesside, passengers expressed their frustration as flights continued to be delayed, even after the problem in Swanwick had been fixed.

David Lowe, 53, an NHS manager, of Darlington, was due to fly to Minorca for a two-week holiday with his wife, Joan when they were told by airport staff to expect a four-hour delay.

Mrs Lowe said: "It seems to be a wait without end. Communication has been abysmal here.

"We are sat here not knowing whether we are going to be waiting for three, four or five hours."

John and Carol Carr, of Tennyson Terrace, Crook, County Durham, were waiting with nine children for a holiday to Ibiza - the first time they had all been away together.

Mr Carr, 48, said: "I am not amused by this. We have had delays at airports before and you are lucky if anyone ever tells you anything.

"One of the main issues with this, especially if you have small children, is the cost of having to buy meals in the airport."

Wayne Theasy, 28, of Hartlepool, who is disabled, was also hit by the delays and had to wait in the crowded departure lounge.

He said: "There are people boarding their flight before us that should not be and we do not know how long we are going to have to wait.

"We have been told we can't leave the airport, so we are stuck here."

John Waiting, spokesman for Teesside airport, said holiday, business and internal flights had been affected by the problems.

He said: "Passengers were advised to continue checking in on time and we made every effort to make them as comfortable as possible while they were waiting for their flights.

"Friday is always a busy day at the airport and no one likes to be delayed, but people were very understanding and seemed to realise they could not fly for safety reasons when the air traffic control system was not working."

Yesterday's problem was the third glitch to hit the UK's part-privatised system recently.

The new Swanwick system has only been operating since January, after repeated software problems delayed its opening and almost doubled its cost.

Yesterday's fault followed a routine upgrade of the control system at Swanwick and was later traced to one or two computers at the centre.

Last night, engineers had still not identified the problem, but ruled that it was safe to return the system to full capacity.

But they warned the backlog could mean delays continuing today.

The UK's air traffic control system handles about 5,000 flights a day, through four centres.

Passengers seeking flight information can contact Teesside Airport, on (01325) 332811, or Newcastle Airport, on 0191-286 0966