The Belgian investment firm RHJ International SA has sweetened its offer for General Motors' Opel unit, saying it would provide $425 million in cash compared to $391 million offered earlier.
It has also cut down loan guarantees from the German government to $4.55 billion from $5.4 billion.
The German government has been insisting on GM to accept the Canadian parts maker Magna International's offer as it has promised not to lay down any jobs. Under the terms of the deal, Magna and Sberbank would get a 55 per cent stake in Opel, while GM would hold onto a 35 per cent stake and Opel workers would get 10 per cent.
Last month Magna said that it had reached an agreement in principle with GM management (See: Magna submits revised offer to GM for Opel).
However, the GM's board was unable to pinpoint a suitable buyer for the unit. (See: Opel talks prolong as GM undecided on Magna offer).
Analysts are expecting that the GM board, which is scheduled to meet again on 8-9 September, will take a final decision on the matter.
In an interview with Bayerischer Rundfunk television broadcast Tuesday night Chancellor Angela Merkel said she hoped that GM could clear up its remaining questions on the matter before national elections on 27 September.
Opel employs 25,000 people in Germany, about half of GM Europe's total work force.