The government has sought to reassure workers after BAE Systems, the UK's largest defence company, revealed plans to sell its 20% stake in Airbus.
Airbus UK is currently making the wings for the new A380 superjumbo
The sale will end British ownership of factories in North Wales and the South West, where some 13,000 people are employed making Airbus aircraft parts.
Trade and Industry Secretary Alan Johnson told the BBC the government remained committed to the project.
But unions have said there would be "tens of thousands of worried people".
Airbus is expected to be bought by Franco-German group EADS.
The group already owns the rest of Airbus.
AIRBUS KEY FACTS
The first ever Airbus, an A300, took off in October 1974
British Aerospace joined the consortium in 1979
There are over 3,900 Airbus jets in service
Airbus employs a total of 55,000 staff Worldwide
Airbus turnover in 2005 was £15.3bn
Mr Johnson, speaking on The World At One programme, said: "The fact that we have such an excellent workforce and such a brilliant role to play here as a centre of excellence for wings doesn't change with the sale of 20% of the shares."
And Tom Williams, Airbus's executive vice-president of programmes, insisted the company was in Britain "for the long term".
"You can be absolutely clear there is no intention of us withdrawing in any way our commitment," he said.
A spokesman for the Welsh Assembly said: "What is important to remember is that companies choose to invest in Wales because it is a great place to do business, not because they are British-owned."
'Centres of excellence'
Unions have said they are pressing for urgent talks with the firm.
Ian Waddell, national officer for aerospace at the trade union Amicus, said there would be "tens of thousands of worried people".
"We want to find out if production will remain in the UK or whether it will be shifted to the countries where the new buyers are based," he said.
But Mark Tami, the Labour MP whose constituency includes the Broughton site, in North Wales, said he was confident the jobs were not at risk.
"Broughton and Filton are the centre of wing-building excellence for Airbus and Airbus would be foolish indeed to abandon that investment and move everything over to France and Germany," he told BBC News.
"I just don't see that happening."
Shadow trade and industry secretary Alan Duncan said: "What really matters to us is jobs and manufacturing in Britain.
"What also matters is the real competitiveness of UK manufacturing and the genuine nature of liberal markets in the EU."
Airbus said in a statement: "There is no surprise about BAE's decision, only in timing.
"Whatever the outcome of the discussions, Airbus is in the UK for the long term and the UK will remain a fundamental part of the Airbus business."
Airbus recently announced the creation of an extra 650 jobs at the Broughton factory in North Wales - the region's biggest manufacturing site with 6,000 staff.
As well as the staff directly employed by Airbus in Britain, as many as 135,000 jobs at UK suppliers are thought to depend on it.
Airbus sold a record 1,055 planes last year, giving it a larger share of new orders than US rival Boeing.
It is thought that BAE sees this as a good time to sell its stake, which could be worth up to £3bn ($5.25bn).
The company is expected to invest the proceeds in its rapidly growing US operations, where it produces 35% of its sales.
Despite a bumper year for Airbus sales in 2005, BAE's commercial aerospace division saw its overall profits fall to £179m from £201m a year earlier because of weak demand for its regional jets.
BAE's move towards concentrating on its defence operations was reflected by last year's acquisition of US firm United Defense for £2.1bn.