The French government has stepped up its search for a buyer for Alstom, the troubled transport engineering group, and is understood to be lobbying Siemens, the German engineering giant, to step in.

According to senior bankers in Frankfurt and Paris, the French government is prepared to turn to Siemens because no French company will bail out Alstom. Marriage talks arranged by the government with Areva, the French nuclear company, collapsed last month.