* State-owned Poste Italiane to take part in Alitalia cash call
* Government demands radical new plan, break with the past
* Government wants help from additional shareholders
* Alitalia board meets on Friday
By Steve Scherer and Valentina Consiglio
ROME, Oct 10 (Reuters) - The Italian government offered financial support on Thursday to help rescue Alitalia using the state-owned post office, but said it wanted radical change at the national airline and shareholders to join a life-saving capital increase.
Alitalia needs 500 million euros ($676.12 million) to avoid imminent bankruptcy and its main fuel provider, Italian oil and gas giant Eni, has threatened to stop supplies this weekend if a rescue plan is not approved.
Poste Italiane, the postal services group which also controls cargo and charter passenger airline Mistral Air, would participate in a capital increase for the flag carrier, the government said in a statement.
The government said it regarded Alitalia - which has not turned in a profit since 2002 and is struggling to keep up payments on one billion euros of debt - as a strategic asset.
However, Rome wanted shareholders, including top investor Air France-KLM, to share in the burden of the capital increase for the airline, which was privatised in 2008.
It gave no financial details but said that if Alitalia could implement a radical change of strategy, the government was ready to help with "the strategic and financial instruments the country can rely on".
Sources close to the situation had told Reuters the rescue plan envisaged the state injecting 150 million euros into the airline, the same amount as existing shareholders, while banks would provide an additional 200 million euros in new loans.
"It's a bridging solution to guarantee the financial survival of the company but it depends on a strong change in the way the company is run," one of the sources said, speaking on condition of anonymity.
Under the rescue plan, Poste Italiane would inject 75 million euros into Alitalia through the capital increase, the sources had told Reuters. The rest of the state help would come in the form of credit guarantees, the sources said.
Alitalia's board is to meet on the bailout plan on Friday.
One source said the government was still pinning its longer-term hopes on a strategic partnership between Alitalia and Air France-KLM, which owns 25 percent of the Italian carrier.
Ministers have approached several state companies in the past few weeks, including railway operator Ferrovie dello Stato, trying to persuade them to stump up funding for Alitalia.
Spain's Telefonica recently did a deal to take over the controlling company behind Telecom Italia. Prime Minister Enrico Letta is loath to see another national asset fail or be sold to a foreign rival without guarantees on safeguarding jobs.
Air France, which is in the middle of a restructuring itself, was barred from staging a full takeover of Alitalia in late 2008 by then-Prime Minister Silvio Berlusconi.
Berlusconi instead strung together a disparate group of 21 investors including retail bank Intesa Sanpaolo and highway operator Atlantia.
Since then, Alitalia has lost nearly 700,000 euros a day and become a symbol of Italy's economic malaise, hampered by mismanagement and political meddling.
Now the government and Alitalia's shareholders are ready to let Air France raise its stake and possibly even take over the group, but there is no agreement with the Franco-Dutch carrier over financial commitments and business strategy.
Alitalia, which according to analysts needs at least 10 million euros a day to keep its aircraft flying, said on Sept. 26 that it had total available cash of 128 million euros, including unused credit facilities.