LONDON (AFP)--The U.K.'s biggest trade union voiced concern over the future of two car plants here Saturday after a deal was agreed to rescue the European arm of General Motors (GM).

The Unite union said it was not certain of the impact of the agreement, which will see Canadian parts maker Magna and its Russian backers take over the operation, as parent company GM prepares to file for insolvency.

"The German government... are clear about the fate of the German plants," Derek Simpson, the union's joint general secretary, told the BBC.

"We should be as clear," he added, but he raised questions about the political leadership in the U.K.

"That's where I think the government has to be more proactive and recognise that it has to some extent been watching in the stands while the action has been taking place on the pitch," Simpson

Vauxhall, the U.K. arm of the business which also includes Opel in Germany, employs around 5,000 workers at two sites in the U.K.

Negotiations over the deal involving German Chancellor Angela Merkel wrapped up early Saturday.

Berlin is expected to give loan guarantees of EUR4.5 billion, including EUR1.5 billion in short-term loans, to keep the company afloat.

Britain's Business Secretary Peter Mandelson said Friday he would be seeking "a reinforcement of the commitment... to continued production by Vauxhall in the U.K." over the deal.