The French and German governments, the most powerful EU member states, have lobbied hard for Europe's competition enforcer to approve the merger of Alstom and Siemens' rail businesses. Their efforts, however, are likely to have been in vain, with the European Commission widely expected to veto the deal on Wednesday.

Among the most radical proposal under consideration by France is to give EU ministers a say when the Commission judges a competition case, the ministry official said.

"The rules need to be revised to allow for European champions to emerge," the official said on condition of anonymity.

"Currently consumers interests take precedence over all other general interests. The aim is to know whether other interests can also take precedence."

France and Germany say that the Alstom-Siemens deal to create a European rail champion is needed to better compete in Europe and abroad with big Chinese rivals, but people familiar with the case expect the Commission to rule that it would reduce choice and competition for EU customers.

France aims to bring forward its competition proposals in coordination with Germany for when the European Commission receives a new mandate late this year, the Finance Ministry source said.

Commission President Jean-Claude Juncker on Tuesday said that the EU executive was not needlessly blocking corporate mergers.

French Finance Minister Bruno Le Maire has called for an overhaul of EU competition rules, which date in their current form from 2004. He says the rules are ill-suited to contend with China's emergence as a major competitor in many markets.

German Economy Minister Peter Altmaier on Tuesday said that he does not favour allowing ministerial approval for deals such as the Siemens and Alstom's deal.

(Reporting by Leigh Thomas; Editing by David Goodman)