* MHI & Siemens CEOs to meet Alstom execs in Paris-sources
* Siemens eyes Alstom's gas turbines business-sources
* MHI eyeing power JVs with Alstom, chiefly in steam-sources
* A formal offer would give govt more leverage against GE
* Siemens & MHI chiefs face French lawmakers on Tuesday
(Rewrites through with background, context on stance of France, Alstom and shareholder Bouygues)
MUNICH/PARIS, June 16 (Reuters) - Germany's Siemens and Japan's Mitsubishi Heavy Industries (MHI) will present a joint offer to France's Alstom in Paris on Monday, challenging a General Electric bid that sparked French government concern about retaining jobs and industry expertise.
Siemens chief executive Joe Kaeser and Mitsubishi chief executive Shunichi Miyanaga were due to meet Alstom officials in Paris on Monday afternoon, a source close to the Japanese firm in France said, and will meet French President Francois Hollande on Tuesday at 0825 GMT, his office said.
Sources close to the bidders say they will propose that Siemens acquire Alstom's gas turbines business while MHI inject cash and industrial assets into a joint venture in steam turbines.
The race to acquire power activities from the French train and turbine maker has entered a crucial week, ahead of a June 23 deadline set by GE for its 12.4 billion euros ($16.9 billion) bid for all of Alstom's energy arm, which includes its thermal power, renewable power and grid businesses.
The French government has criticized GE's proposal and gave itself powers to veto a deal on the grounds it does not want Alstom, an innovator and big employer, to sell the bulk of its business to a foreign firm without the state having a say.
The government has also tried to negotiate better offers and alliances to preserve Alstom as a player in both transport and energy, seeing both as vital national industries at a time when unemployment is stuck above 10 percent and a growing chunk of voters are turning towards the far-right.
The Siemens-Mitsubishi plan, which was discussed by Siemens' supervisory board late on Sunday, would not be a direct buyout of Alstom's power assets but instead set up one or several joint holdings in its power businesses, including in hydroelectric power equipment and grid, said two sources with knowledge of it.
The deal would comprise a cash element that could reach around 9 billion euros, those same sources said - including a payment of 4 billion by Siemens for the gas turbines business and Mitsubishi's cash injection in the steam turbines joint venture and payment for a direct stake in Alstom.
Alstom, best known overseas for making TGV high-speed trains, employs 18,000 people in France, or around a fifth of its workforce. It was rescued from near bankruptcy by the state a decade ago and has since largely relied on public orders for power and rail equipment.
A formal rival offer would give France more leverage against GE as it seeks more job guarantees and a promise to keep major offices in France to secure the nation's energy independence. Alstom is a supplier of turbines for nuclear plants worldwide, and Paris fears that having these fall under U.S. control could jeopardise exports in the atomic power industry.
However, it is far from certain whether the government, Alstom and its top shareholder Bouygues would genuinely support a Siemens-Mitsubishi offer over that of GE.
Several sources familiar with Alstom's thinking warned that the Siemens-Mitsubishi plan, as it was shaping up, would break up Alstom's power business and ultimately run counter to the government's aim of preserving the group's integrity and scale.
"We'd be looking at a real dismembering of Alstom," said one of the sources. "It all sounds a little whimsical. Alstom is a privately-owned company, but the government is acting as if it were nationalised."
Alstom declined to comment. Bouygues said it had not been approached by any party regarding a buyback of its stake in Alstom. It said it would support the proposal recommended by Alstom's board and wished to remain a long-term shareholder with a 29.3 percent stake - its current level.
Siemens' Kaeser and MHI's Miyanaga will present the plan to France's lower house of parliament at 1500 GMT on Tuesday, according to the parliamentary press office, and are likely to face questions from lawmakers worried about national interests.
The government has already secured a pledge from General Electric to create 1,000 new jobs in France within three years of a deal, but Finance Minister Michel Sapin said on Sunday he expected the U.S. conglomerate to further improve its offer.
GE is ramping up its charm offensive in the French press with new ads saying its proposed "alliance" with Alstom would create a global energy leader based in France while strengthening Alstom's transport business.
"Tomorrow is made in France," the ads read, below a drawing of an airplane - a hint at the jet engines GE makes via the U.S.-French venture CFM - flying over a field of wind turbines.
GE Chief Executive Jeff Immelt told French lawmakers last month his group would set up global headquarters for the grid, hydro, offshore wind and steam turbines businesses in France. GE is also considering a tie-up in rail signalling that would give Alstom control of that business, he said.
The government is worried that Alstom would be too weak once reduced to its smaller transport arm, and has played up an alternative tie-up with Siemens, which also makes trains, as an opportunity to create a European rail champion.
But Alstom has not shown interest in Siemens's rolling stock, and according to sources close to the talks, Siemens is now expected to propose a transport deal only at a later stage in the negotiations, as something entirely separate from any turbines deal.
($1 = 0.7345 Euros)
(Additional reporting by Elizabeth Pineau and Natalie Huet in Paris; Writing by Maria Sheahan and Natalie Huet; Editing by Sophie Walker)