BAE Systems has put in a revised bid for a £4bn armoured vehicle contract and warned the government that its tank factory in Newcastle may have to close if its bid fails.The company has promised to create and protect 800 jobs if the Ministry of Defence goes with the UK firm, although it has stiff competition from the Americans.Reports suggest US rival General Dynamics (GD) is close to securing the contract for at least 750 Future Rapid Effect System (FRES) vehicles.It has already said 80% of the manufacturing would be completed in Britain, safeguarding or creating around 10,500 jobs.BAE, which sacked 500 workers at its armoured vehicles division last year, says the remaining 800 staff at the unit face an uncertain future if GD wins.It's believed the old Armstrong Whitworth factory on the Tyne, which employs about 450 people, could be closed.And the omens aren't good. A consortium of which Sikorsky is a member was last month awarded a £5bn deal to provide S-92 search and rescue helicopters, while Boeing won a £1bn order for 22 CH-47F Chinook helicopters in December.