Germany sought to shore up its rescue plans for carmaker Opel as Spain and Britain fought to safeguard their own Opel plants and domestic critics laid into the Berlin-brokered deal with Canadian automotive firm Magna.

The German Economy Ministry on Friday held talks with officials from other states that host Opel plants, as Berlin moved to quell fears of splits arising over how job cuts and financial support for the carmaker were shared out.

After meeting co-chief executive Siegfried Wolf, Spanish Industry Minister Miguel Sebastian said his country was not yet convinced by the sustainability of Magna's plans, and would not offer any financial support before this was resolved.

It was a very cordial meeting, but it was clear that we still have a long way to go, Sebastian told reporters in Berlin, speaking through an interpreter.

There had been a communication problem between Magna and Spain over the future of the country's Zaragoza plant, Sebastian said, but added the firm was convinced the works had a future.

A spokeswoman for the British government's business department said talks with unions and Magna over the future of the UK plants would have to continue.

We have not yet reached a conclusion which is acceptable to either the union or the government, said a spokesperson for the government's business department after talks involving Business Secretary Peter Mandelson.

Magna and its Russian partner Sberbank (SBER03.MM) have vowed to inject 500 million euros into Opel, which they want to use to make an aggressive push into the Russian market.

They plan to cut some 10,500 European jobs, of which about 4,000 in Germany, but have committed to keeping all the German plants running. Opel's Antwerp plant in Belgium and the UK manufacturing site of sister brand Vauxhall in Luton are seen to be most at risk.

In order to push through a deal, Germany offered to stump up 4.5 billion euros in guarantees for Opel, saying it would agree later how this was split between countries with plants, which include Poland and Belgium as well as Britain and Spain.

LITTLE TO OFFER

Spain has been worried that jobs in Zaragoza could be lost to a German plant in Eisenach, and Sebastian said any shake-up had to ensure that other factories less or no more competitive than the Spanish site did not profit from it.

Britain's Mandelson has said the British government would not back Magna's plan to buy 55 percent of Opel from General Motors in its current form.

However, his ministry said on Friday that London could offer funding for the deal if a long-term plan for sustaining its Vauxhall works in Britain could be found.

It's a question of us wanting to be sure of securing the best deal for Vauxhall in the UK, a spokeswoman said.

Around half of Opel's 50,000 European jobs are in Germany.

Sebastian said Spain had chosen not to participate in the multilateral talks in Berlin because Madrid had very little to offer at present. A spokesman for the German Economy Ministry said Friday's talks had been constructive.

A meeting between Magna and Spain is due to take place in the Spanish capital on Tuesday, Sebastian said.

Domestic headwinds for the deal are also growing in Germany.

The market-liberal Free Democrats (FDP), which are in negotiations to form a new government with Chancellor Angela Merkel's conservatives, raised fresh concerns on Friday.

Deputy FDP leader Rainer Bruederle criticised the plans, and said he wanted to raise the matter in the coalition talks.

My fears are gradually being realised that nothing has been properly worked out on this, he told reporters.

Klaus Franz, German head of Opel's works council, said on Friday he did not expect workers to scupper a deal, despite tough negotiations over making sacrifices on pay.

However, for this to be assured, plans to put a 10 percent share of Opel in workers' hands needed to guarantee them the same rights as other shareholders such as Magna and Sberbank.

Sebastian was due to hold talks with his German counterpart Karl-Theodor zu Guttenberg later on Friday. The German Economy Ministry said these were likely to remain behind closed doors.

(Additional reporting by Markus Wacket, Thorsten Severin, Angelika Gruber and Keith Weir; editing by John Stonestreet/Will Waterman)