Between 400 and 500 of the posts are to go at the Transit plant in Southampton. The firm said it hoped the losses would be met through voluntary redundancies.
Bosses will also renegotiate a recent pay deal struck at the south coast site and have postponed a decision on the future Transit production at the plant.
The GMB union accused Ford of “going back on its agreement” over a 5.25% pay increase agreed late last year.
Gary Alexander, a worker at the factory for 20 years, said: “It’s doom and gloom here at the moment and I think this factory’s days are numbered.
“They [Ford] went back on their word about the pay offer and they said there would be no more job losses.
“They said the redundancies will be voluntary but they will not get that many.”
He ruled out a possible strike by saying “nobody wants that”.
Justin Bowden, GMB union officer, said: “Ford of Europe made a profit in excess of £1bn in 2008.
“The pay offer reflects last year’s rate of inflation and the massive contribution to that profit by the UK Ford workers.
“Yet again Ford is going back on its agreement with its workforce and this time it is on pay.”
Another worker at the Southampton factory said a mass meeting had been planned for 1000 GMT.
“I have only worked here two years so I hope it is not last in, first out,” he added.
“But apparently it isn’t going to be like that and they are looking to limit any compulsory redundancies.”
Mrs Gidley, Lib Dem MP for Bassett and Swaythling, said the announcement was “tragic news” and claimed the government had been “slow to act”.
She added: “This is tragic news for the plant, the workers and the city.
“That is bad enough, but Ford are creating extra uncertainty by renegotiating the recent pay deal.
“I have been consistently raising concerns for some months, but the government have been slow to act.”
She said she was seeking a meeting with Business Secretary Peter Mandelson over the situation.
Ford bosses blamed the “unprecedented” economic conditions for its decision.
John Fleming, Ford of Europe chairman and CEO, said: “As demand across the industry continues to fall, we are facing some immediate and major challenges.
“Those companies which act quickly in taking the right decisions will be those who not only survive but who emerge strongest from this deep recession.”
The announcement comes as new car registrations fell by 30% in January, the Society of Motor Manufacturers and Traders said on Thursday.