But the stoppage, scheduled to begin at midnight on Monday, still looks likely to go ahead after the director general, Mark Thompson, reiterated that his plan to cut 4,000 jobs and slash budgets by 15% was the only way to reform the BBC for the digital age.
The National Union of Journalists, broadcasting union Bectu and Amicus confirmed they had agreed to meet BBC management for talks on Thursday but said that there would have to be "meaningful negotiations" on the number of redundancies if the strike was to be averted.
"At this stage the 48-hour strike scheduled for May 31 and June 1 is still going ahead as we have no knowledge of what the BBC may or may not offer," said Bectu BBC supervisory official Luke Crawley.
Earlier, the unions clashed with Mr Thompson over who was to blame for the strike.
"We were disappointed when the unions decided to walk away from the table and go for a strike ballot. At no point have we said to our unions there is anything we can't discuss," Mr Thompson insisted, adding that the corporation was prepared to be "very flexible" about how the cuts were made.
But the unions replied that the BBC had already made its mind up about the cuts, designed to save £355m annually to reinvest in programming and new distribution networks, and was "lecturing rather than negotiating".
Mr Thompson admitted that there was unlikely to be any other way of achieving the cost savings required to secure the licence fee and safeguard the future of the BBC.
"We can't make the need for change or its scale go away. We have set out a plan for the future and a budget for the BBC over the next few years, and we can't unwish that," Mr Thompson told the Westminster Media Forum."We came up with the proposals for staff numbers after many months of discussion. I would be surprised if we could find a way of shifting those significantly."
Mr Crawley said that the BBC had not so much held out an olive branch as "a stick with the leaves missing". But both sides said that they would arrive at Acas with no preconditions. They will initially sit in separate rooms, with Acas officials acting as go-betweens.
Meanwhile, BBC chairman, Michael Grade, said it would be "wholly inappropriate" for the governors to meddle in the dispute. The dispute overshadowed the BBC's response to the green paper on its future and funding, which it broadly welcomed.
But Mr Grade said the corporation fundamentally differed with the Department for Culture, Media and Sport over its aim to investigate the idea of "top slicing" the licence fee to fund public service programmes by other broadcasters after 2012.
· More viewers tuned into watch BBC World newscaster Stephen Cole front the Ten O'Clock News on Monday than normal. Some 5.6 million viewers tuned in, 200,000 up on the previous week hosted by Huw Edwards. Cole is not alone in receiving more viewers. Anna Ford's One O'Clock News slot was taken by Susan Osman, with 300,000 extra viewers.
A spokesman put the success down to fascination with how the BBC would cope.
