Opel dealers in Europe are offering to help the ailing German carmaker by investing 500 million euros (679 million dollars) in return for a 10 to 15 per-cent stake, dpa quoted the dealer group as saying today in Vienna. Meanwhile, there was opposition from the administration in the United States against Germany's plan to put Opel under temporary trusteeship of the state until an investor is found, according to media reports. All 25 national members of the Euroda association - except for Finland - had approved the dealers' offer at a meeting in Austria's capital, the group's chairman Jaap Timmer told reporters. "In return, we demand a fair equity share in the new company, representation in the supervisory board, and obviously, a fair financial return on our investment," said Timmer, whose association also represents Vauxhall dealers. The plan is to pay 150 euros for each sold car into an emergency fund over the coming three years to contribute to Opel's rescue, as 35,000 retail jobs are at risk in Germany alone. Timmer said it would hurt retailers to pay into the fund, especially those in Central and Eastern Europe, "but it would be far worse if we had no manufacturer at all." Euroda is now set to start talks with the players who would have to support the offer, including the government in Germany and other countries where Opel cars are made, as well as potential investors such as Italian carmaker Fiat or Canada-based car industry supplier Magna. Timmer said that he had received positive signals from Opel, which is a subsidiary of close-to-bankrupt US automaker General Motors, and that the German government was informed. German Economics Minister Karl-Theodor zu Guttenberg announced Berlin's intention Thursday to fence off General Motors' assets in Germany and place them in a trust if the US parent fails. However, Washington does not support the idea, the German dailies Financial Times Deutschland and Frankfurter Allgemeine Zeitung reported Friday.