Almost half of the BBC's 27,000 staff mounted the corporation's biggest strike in more than a decade today throwing its live broadcasting schedule into disarray.

Although union leaders failed in their attempt to reduce the service to "blank screens and dead air", rolling news and current affairs broadcasts on radio and television were severely disrupted after the walkout which began at midnight.

The industrial action, supported by at least 11,000 of the corporation's workforce, has been launched in protest at the loss of 3,780 jobs over the next three years and across-the-board budget cuts of 15 per cent.

Three unions, the National Union of Journalists (NUJ), Amicus and Bectu, claim that the cuts are "savage" and will cause irreparable damage to a "national institution."

Mark Thompson, the BBC Director-General, has argued that the £355 million released by the cuts will be invested in technology, crucial if the corporation is to survive in the new era of digital broadcasting.

Union members this morning manned a series of picket lines around the main BBC buildings - Bush House in Central London and Television Centre/Broadcasting House in West London - as the skeleton staff of strike-breakers and freelancers kept a slimmed-down news service on air, buttressed by repeats.

One of the biggest demonstrations was held was outside Television Centre where journalists and technicians were joined by Brendan Barber, the TUC general secretary, and veteran campaigner Tony Benn. The journalists held up banners which read: "We’re on strike to save the BBC!"

The BBC reported at noon that 55 per cent of its staff had gone to work as normal and there was some solace for managers when a series of high-profile presenters chose to break the strike.

Nicholas Witchell, the royal correspondent who was famously branded a "scab" at the 1989 strike, was at work. This time he was joined by Radio 5 breakfast host Shelagh Fogarty, Radio 3 breakfast presenter Terry Wogan and Radio 1 breakfast show host Chris Moyles, whose main complaint was that his studio webcam was out of action

At 8.30am Radio 1 presenter Jo Whiley arrived at Broadcasting House. She made no comment as she walked into the building, but did take a strike leaflet from union members.

The morning Radio 4 news programme Today, which includes politicians and newspaper editors among its daily audience of 6 million, was the most high-profile casualty of the industrial action. Its political interviews, led by John Humphrys, typically set the day's early news agenda.

Mr Humphrys told London's Evening Standard newspaper that he was once an union official and that although no longer a member, he: "did not like crossing picket lines."

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