Opel chairman Nick Reilly has said General Motors was "very satisfied" with progress at Opel, but stopped short of commenting on whether the European unit had been put up for sale.

"General Motors is very happy with the fact that Opel/Vauxhall is ahead of plan in terms of restructuring," Reilly said in a written statement released following a meeting of the supervisory board, Reuters reported.

But Reilly failed to quash rumours that GM was mulling a sale of the European brand, saying only that GM "does not comment on speculation."

The statement said GM would not deviate from this policy of no comment, particularly since it had a "responsibility toward shareholders" and needed to comply with the rules of a stockmarket-listed company.

A GM spokesman in Detroit declined to comment to Reuters beyond the statement out of Germany.

Rumours GM was in talks to sell European carmaker Opel surfaced earlier this month, but a German newspaper reported that GM chief executive Daniel Akerson has reassured Opel that it was not in talks to sell it.

GM Europe posted a profit in Europe during the first quarter and Opel increased monthly market share for the seventh month in a row on a year-on-year basis, Reilly said.