Unions were today calling for urgent talks with BMW over the future of Rover as the clock began ticking on the deadline for saving the huge Longbridge factory from closure.

The German car-maker has warned it will close Rover, including the Birmingham plant, within a month unless a sale can be agreed.

The deadline was set after talks with venture capitalist firm Alchemy collapsed.

The breakdown leaves a rival bid, led by former Rover executive John Towers, in the driving seat to buy the loss-making company.

Sir Ken Jackson, of the Amalgamated Engineering and Electrical Union, said: "BMW should now meet us to discuss where we go from here. "We need to be certain that it is serious about securing the future of Rover."

Workers at the Cowley car plant at Oxford are still waiting to hear how the breakdown in talks between BMW and Alchemy Partners will affect their future.

BMW said it plans to develop the 700m plant into a major production centre to build the new Mini and a new range of small BMW cars. But it is believed that the Towers-led Phoenix consortium's bid for Rover includes taking over Cowley as well as the Longbridge plant.

Mark Norman, of the CAP motor research company, said: "The Phoenix bid looks eminently sensible if it can get the financial backing. "Workers at Longbridge may have been cheering about the collapse of the Alchemy bid, but at least it provided something of a safety net.

"Now there are real fears that this could be the end for Rover."

Oxford East MP Andrew Smith said: As soon as I heard the Alchemy news, I got on to BMW. It assured me that none of this changes its plans to keep the Cowley plant, to continue employing the workforce and to build the new Mini here."