The supervisory board of General Motors'
The supervisory board was set to approve a transfer of Opel's non-German European plants to German unit Adam Opel GmbH, the person said.
Financially, Opel is already separate from the parent company, a source has told Reuters.
The German government is due to decide on Wednesday which bidder or bidders it prefers as a partner for Opel. It wants to act quickly in case GM files in the United States for Chapter 11 protection from creditors.
Chancellor Angela Merkel's government has been considering offers from Italian carmaker Fiat
In an unexpected twist, Chinese carmaker Beijing Automotive Industry Holding Co (BAIC) has emerged as a last-minute contender.
(Reporting by Angelika Gruber; Writing by Maria Sheahan, Editing by Michael Shields)