General Motors is prepared to hand over part of Opel without setting a price for the German unit, company sources told a newspaper.

The potential investor would provide only a capital injection of at least EUR500m, the sources told Financial Times Deutschland.

Private investor interest is crucial for Opel's future independence, the paper noted.

German chancellor Angela Merkel Merkel told workers at Opel's main plant in Frankfurt on 1 April that the government could use loan guarantees to help entice investors but ruled out a state stake.

GM CEO Fritz Henderson on Friday said he was confident that negotiations with potential buyers would be completed early in May, adding that there now were "over six" serious candidates.

The FTD said the readiness of the US parent to give up part of Opel with no gain signified the difficulties it has encountered while seeking a private investor.

GM would otherwise soon be forced to give Opel a capital injection and would benefit from fresh capital from a new investor, in view of its desire to keep a minority share in its German unit, the paper said.

GM has previously promised to grant Opel assets in form of investments, patents and cash worth EUR3bn while Merkel has said Opel and UK subsidiary need around EUR3.3bn to survive.

Opel would get part of the GM assets in exchange for giving up possible future claims against its US parent, the FTD added.