FRANKFURT: Porsche, the maker of German luxury sports cars, rejected on Monday a merger offer by Volkswagen, Europe's biggest car maker.

"There is an offer by Volkswagen. For us it is not a practical way," a Porsche spokesman told AFP.

As a result, a credit worth 10.75 billion euros (15 billion dollars) agreed to by a consortium of banks would come due "right away," he added.

A press report said over the weekend that VW had presented a merger proposition to Porsche which would proceed via cross shareholdings, with VW taking a stake of 49.9 percent in Porsche.

Porsche currently owns 51 percent of the shares in VW.

The plan "was transmitted to Wolfgang Porsche last week," but "it has not been brought to the attention of the Porsche board," the spokesman said.