Fiat has provided further detail on its bid to buy General Motors' European operation Opel and Vauxhall.

Karl-Theodor zu Guttenberg, Germany's economy minister said that Fiat had provided more detail about capital contributions and risk-sharing. Fiat is planning to cut approximately 10,000 jobs if its bid is successful.

German government officials are currently discussing rival bids from Canadian car parts maker Magna and RHJ International, a Brussels-based investment firm.

Zu Guttenberg told German newspaper Bild am Sonntag: “Fiat has improved its offer once again and we've received a more thorough blueprint from them in the last few hours.

"We're sensing a willingness to negotiate further from all sides. We must first have a high degree of certainty that the significant tax money we will have to provide is not lost. From my point of view, none of the three offers so far provides this certainty in a sufficient way."

Roland Koch, the premier of Opel's home state of Hesse, said the Magna offer was "closest to the hopes and wishes" of German politicians and the country's Opel workers.

German foreign minister Frank-Walter Steinmeier described the Magna bid as the only "sustainable" plan among the three.

GM is aiming to sell Opel ahead of a June 1 US government deadline to restructure its finances or face bankruptcy protection. GM is also looking to sell Sweden-based Saab, its other European car business.