France said it would defend jobs and its national interest as it met suitors for engineering group Alstom, suggesting Germany's Siemens may have an edge over General Electric.
President Francois Hollande has held talks with GE boss Jeff Immelt and was due to sit down later with Siemens CEO Joe Kaeser to discuss the fate of Alstom.
The company makes France's prestigious TGV high-speed trains and turbines for power plants.
"We won't let Alstom sell this national champion behind the back of its shareholders, its employees and the French government," Economy Minister Arnaud Montebourg wrote on his official Twitter account before the meetings started, accusing Alstom's CEO Patrick Kron of "a breach of national ethics".
Alstom, which is suffering from big debts and falling demand, was bailed out by the French government in 2004 but now needs help again.
Smaller than its rivals, it was hit the hardest by a slump in orders for power equipment since the 2008 economic downturn depressed electricity prices.
Outside of France, Alstom is involved in a large number of projects, including the supply and maintenance of trams for Dublin’s Luas system and the construction of some energy generation facilities across Ireland.
Today’s meetings follow a weekend of drama when Alstom's German rival Siemens proposed a swap of power and rail assets to counter a potential Alstom-GE energy tie-up.
Berlin weighed in this morning, saying an Alstom-Siemens deal would be "a great opportunity" for Franco-German cooperation.
After GE CEO Immelt emerged from talks at the presidential palace the company issued a statement saying: "The dialogue was open, friendly and productive."
It added: "It was important to hear in person President Hollande's perspective and to discuss our plans... We understand and value his perspective, and we are committed to work together."
A source with knowledge of the meeting said Mr Hollande was looking closely at jobs, the nation's energy independence, and the location of activities both in power and rail.
The source added GE had offered some solutions to these concerns but that there was still a lot of work to do.
Mr Montebourg said before the meeting with GE that France would oppose any deal it considered unsuitable.
But the minister – who has threatened in the past to nationalise assets belonging to steelmaker ArcelorMittal - stopped short of suggesting the state would do the same for Alstom.
"It's too early to raise that question," he said.
Mr Hollande will meet Siemens' Kaeser in the evening and later hold talks with Martin Bouygues, the billionaire chairman of family conglomerate Bouygues that is Alstom's largest shareholder with a 29.4% stake.
Mr Immelt arrived in Paris during the weekend, aiming to hammer out a $13 billion deal to buy Alstom's power turbines business.
News of talks between the two surfaced last week and sources with knowledge of them say they have been going on for months and are very advanced.
Analysts see sense in an Alstom-GE tie-up.
GE is relatively weak in turbines for nuclear and coal power generation, where Alstom is strong; its established base of power installations generated 70% of its global revenue in the last year.
A deal would also enable GE to expand into offshore wind power and grid technology.
Such a beefed-up GE would be a tough competitor for Siemens- hence its counter-attack, say industry sources.
Citi analysts estimate that combined with Alstom, Siemens could have 50% of the world's installed power capacity, well ahead of GE, which currently has around 25-28%.
Germany's Siemens, like Alstom, makes high-speed trains and other rolling stock as well as power station turbines, and is reportedly proposing an asset swap that would make Alstom a more significant rail transport player while enhancing its own turbines and power grid equipment business.
However, industry sources and analysts say that a deal with Siemens - an option floated a decade ago but rejected by both Alstom's CEO Kron and then-president Nicolas Sarkozy – could bring more overlap and antitrust issues than a deal with GE.
Alstom's unions warned a Siemens tie-up implied big layoffs at both companies due to heavy overlap.
Alstom employs 18,000 people in France, about 20% of its total workforce, against GE's 10,000 French workers and Siemens' 7,000.
"Why not a Franco-French solution? Can't the French state intervene directly by partly taking over the stake Bouygues holds?" Alstom's moderate CFE-CGC union said in a statement.
Labour Minister Francois Rebsamen, asked if nationalisation remained an option, told France Inter radio: "I think nothing is out of the question at the moment."
GE has declined to comment apart from today’s brief statement. So has Bouygues, only saying it supports Alstom's strategy. Siemens said yesterday it had written to Alstom about strategic opportunities but also did not go into detail.
Alstom said in a statement yesterday it would ask for a suspension of its shares until Wednesday while it considers its options.
Alstom shares, which had slumped earlier this month to a near nine-year low, jumped at the end of last week to reach their highest in five months.