FRANKFURT (Reuters) - Deutsche Bank and Commerzbank’s chief executives have resumed talks over a potential merger, Focus magazine reported on Friday.

However, two people familiar with the matter told Reuters that Deutsche Bank and Commerzbank’s top managers had no mandate from their respective supervisory and management boards for any talks about a merger of Germany’s two biggest banks.

“There is no official mandate for merger talks with Commerzbank,” one of the people told Reuters, contradicting the sources in the Focus report who said the CEOs had received the go-ahead for negotiations.

The second source said it was “total nonsense” that the boards had given their chief executives the go-ahead to begin talks and there had been no recent discussion at Commerzbank’s supervisory board about a merger with a larger rival.

Spokesmen for Deutsche Bank and Commerzbank declined to comment on the Focus report which cited people familiar with the matter who said Deutsche Bank CEO Christian Sewing and his counterpart at Commerzbank, Martin Zielke, have been in intense talks for some days.

Deutsche Bank shares traded 0.5 percent lower early in Frankfurt, while Commerzbank was 0.1 percent higher.

Speculation of a merger has heightened under the tenure of Finance Minister Olaf Scholz, who has spoken out in favor of strong banks. Both banks have been slow to return to sustainable profitability since the global financial crisis.

Last week, a person familiar with the matter said that U.S. investor Cerberus Capital Management, a major shareholder in both Deutsche Bank and Commerzbank, is open to a merger, raising the chances of a tie-up.

Deutsche Bank, regarded as one of the most important banks for the global financial system, has been plagued by three years of losses, ratings downgrades, failed stress tests, and money laundering scandals. Commerzbank is still partially owned by the German government after a bailout.