A German government minister has ruled out General Motors inserting a clause in any Opel sale deal to buy back majority control later.

“This is incompatible with our views and cannot happen,” economics minister Karl-Theodor zu Guttenberg told German Sunday paper Frankfurter Allgemeine Sonntagszeitung.

The comments could suggest that Belgian financial investor RHJ International may have problems with its bid if the company is viewed as only a short-term player, Reuters noted.

Germany, expected to shoulder the bulk of the billions in loan guarantees as part of a deal, and state and federal governments represented on the board of a trust that has to approve a sale of Opel, clearly do not want taxpayer money used as a short-term fix to help a major multi-national out.

According to the report, the minister also warned that Opel bidders would have to invest more of their own capital for the package of state aid to obtain EU clearance, otherwise only taxpayers’ interests would be aty risk.

Zu Guttenberg said the size of the state aid requested would not be the deciding factor alone for Berlin.

“That’s too simple. What good is an offer that is cheap (to the taxpayers) if the return of the money is in question. The key will be if a concept is so sustainable that there is a high probability that the interest, fees and the money can be paid back,” he said.

When asked what was sustainable he responded: “A competitive company that urgently addresses the need to consolidate (capacity and staff).”

Magna , RHJ and Beijing Automotive have been in a race to acquire Opel and final binding offers are due at close of business on Monday.

BAIC has requested only EUR2.64bn in state aid, while RHJ wants EUR3.8bn and Magna EUR4.5bn but the Canadian group is seen as heavily favoured within Germany – a country where the short-term time horizon associated with financial investors is viewed with suspicion, the news agency noted.

Some executives at GM unhappy about losing control over Opel are pushing for a deal with RHJ in part because of the higher likelihood that the Detroit carmaker could reacquire control over its former German subsidiary, sources familiar with the talks told Reuters.