More than 20,000 people travelled on the buses for free on one of the busiest days of the year because of a computer glitch.

Ticket machines on almost 200 Brighton and Hove buses were out of action for about six hours on Saturday.

Drivers were instructed to wave passengers aboard without charging them as the city teemed with visitors enjoying the sunshine and temperatures approaching 20C.

Roger French, managing director of Brighton and Hove Bus and Coach Company, said a software bug had knocked out 90 per cent of the bus machines.

He said: "It was a one-off - at least it had better be!

"But I hope everyone enjoyed their free travel while it lasted."

The company is now totting up how much money it lost in the six hours and will present a bill to its software supplier which could be as much as £30,000.

Bus staff arrived on Saturday morning to discover software which was being installed on a central computer overnight contained a bug.

Mr French said: "We could not just stop the service so we sent the drivers out and people travelled free until we managed to get the problem fixed around lunchtime.

"It's quite normal practice for us to upload software like this overnight but it has never gone wrong before, certainly not on this scale.

"This particular software was meant to fix a minor fault we had so it failed spectacularly.

"We've been made a victim of modern technology but we will be putting in a claim to the manufacturer.

"Although it was a busy Saturday it was far better that it happened then than on a weekday when we are carrying a lot of people to work and school."

Teacher Ruth Power, 28, of Holland Road, Hove, said: "It was a lovely surprise. I just strolled on to the bus without paying on the way into town and did the same thing on the way back.

"Word spread that the buses were free and I think people took full advantage of it. I know I did.

"The buses were really busy, much more so than on an average Saturday. They should do it more often."

One bus driver told The Argus: "I came on at around 6.15pm and by that time it was all fixed but a few passengers commented and were disappointed when I asked them for money.

"I bet it was nice and easy for the drivers and the passengers had a whale of a time but don't expect it to become a habit."