BBC television channels including Freeview face severe disruption later this month after union members in the corporation's technology arm voted overwhelmingly to take industrial action.
Union members in BBC Technology voted to strike just 24 hours after the subsidiary that supplies BBC channels with transmission and other services was acquired by German electronics giant Siemens.
More than four in every five workers voted to strike after the sale sparked concerns over future staffing levels and terms and conditions. The union also opposes the September 1 transfer of ownership date as too soon to allow proper negotiations.
Bectu said it aimed to give BBC Technology a timetable for strike action next week.
The action, which could begin as early as July 21, could decimate the technical side of the BBC just days before the corporation starts broadcasting the Athens Olympics.
"We're obviously aiming to have the maximum effect in terms of disruption. The best of all possible worlds would be blank screens," said the BBC division's senior officia, Luke Crawley.
"We can't say that's going to happen - but as the division controls nearly all the programme feeds routing through the BBC, management could have issues fixing any technical problems. It's not as easy as it used to be."
Members of the union have opposed the sale since it was announced last year by former director general Greg Dyke in a bid to cut costs.
Bectu said it expected the sale to exceed the £20m-£30m annual savings targeted by Mr Dyke, which the union has argued could be achieved by keeping the unit in house.
The sale still has to be approved by the BBC's board of governors - expected to be granted next week - and the backing of culture secretary Tessa Jowell.
The union, however, said it would continue negotiations with Siemens after a preliminary meeting yesterday morning.
During the meeting the German company promised there would be no compulsory redundancies among the subsidiary's 1400 staff for 12 months, but refused to agree to union demands to extend that to three years.
Bectu also expressed concerns that the German company would not agree to the transfer of BBC final salary pension schemes.
"Managers from Siemens confirmed that although the company was willing to establish a pension scheme 'broadly comparable' to the BBC, and would retain many BBC terms and conditions, they could not agree to most of the union's demands for long-term guarantees that staff would not suffer adverse changes," Bectu said in a statement.
It accused the BBC of handing a plan to the bidders including secret proposals for up to 350 job losses.
The BBC refused to show the plans, dubbed Project Leo, to the union.
"Given that BBC Technology is actually the nervous system of the BBC and is central to the convergence of broadcasting and information technology, it is a proposal which makes no sense," Bectu said in a letter to BBC chairman Michael Grade.
"Any new owner will insist on making a profit on the operation, so it is likely to cost the BBC significantly more than retaining it in-house," the union added.
The BBC said yesterday that the sale of its technology arm to Siemens demonstrated the best value for money, cultural fit and scale.
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