German engineering group Siemens and Mitsubishi Heavy Industries are expected to present their joint move on France's Alstom in Paris on Monday, challenging a formal offer from General Electric.

According to sources close to the bidders, the German firm would acquire Alstom's gas turbines business under the deal, while the Japanese group would inject cash and industrial assets into a joint venture in steam turbines.

The Siemens-Mitsubishi plan would not be a direct buyout of Alstom's power assets but would rather set up one or several joint holdings in power, sources have said.

Siemens Chief Executive Joe Kaeser is to present the joint offer with Mitsubishi to Alstom's management on Monday afternoon and outline details of the plan at France's parliament on Tuesday, several people familiar with the matter said.

The offer comes ahead of a June 23 deadline set by GE for its 12.4 billion euro ($16.9 billion) bid for all of Alstom's energy arm, which includes its thermal power, renewable power and grid businesses.

The rival approaches have prompted the French government to press for jobs guarantees as it sees the group's transport and energy activities, notably in nuclear power, as strategic at a time when the country's unemployment rate is stuck at above 10 percent.

In a second step, separate to a turbines deal, Siemens is also to propose combining its rail activities with Alstom's, known for the high-speed TGV trains, sources have said. The French government has actively lobbied for this, saying it would create a European rail champion.