* Poste willing to invest up to 40 million euros
* Poste unwilling to take on Alitalia's liabilities
* Etihad plans to take 49 pct stake in Alitalia
* Etihad expects to finalise deal with Alitalia this month
By Massimiliano Di Giorgio and Agnieszka Flak
ROME/MILAN, July 21 (Reuters) - Poste Italiane will only invest more money in Alitalia if it avoids taking on the airline's past liabilities, three sources close to the matter said on Monday, a condition likely to hamper a rescue deal with Etihad Airways.
Abu Dhabi's state-owned Etihad plans to buy 49 percent of the loss-making airline in a deal the Italian government hopes will make Alitalia profitable again.
Poste Italiane, the state-owned Italian postal services company, is Alitalia's second-biggest shareholder with nearly 20 percent. Its position on the airlines past liabilities could derail a deal that has been in the works for months.
"The move is a big obstacle to an agreement because Poste has the same duties as other shareholders," one of the sources said, adding that meetings were planned in the coming days to try and resolve the impasse.
Etihad said last week it expected to conclude the deal this month, though the deadline may be extended.
Poste Italiane invested 75 million euros ($101 million) in Alitalia late last year as part of a 500 million euro government-engineered rescue package to keep Alitalia flying while it sought a foreign investor.
Alitalia risks having to ground its planes unless an agreement with Etihad can be pushed through.
As part of the Etihad deal, all shareholders are being asked to participate pro rata in a 200 million euro share issue to cover any losses Alitalia is likely to make before the deal is finalised, and to pay for any past liabilities, sources said.
That would mean a 40 million euro investment from Poste Italiane. Sources said the group was only willing to invest in a new company that will be created under the Etihad deal, not the holding company that will take on Alitalia's debts.
"We are not pulling out, but we will come on our own conditions," a second source said.
Poste Italiane's past investment in Alitalia is already subject to an EU investigation as to whether it complied with state aid rules.
STATE AID RISK
Under the deal with Etihad, Alitalia will be turned into a holding group and take on most of the airline's liabilities.
Its business operations, including its fleet and flying slots, will be put in a new company controlled by the holding company. Etihad will invest in the new company via a separate capital increase, sources have said in the past.
Poste is willing to invest up to 40 million euros directly in the new company in return for a stake of around 5 percent, the second source said.
"Poste is already being observed by Brussels for its entry into Alitalia ... if we now participate in a capital increase, we would risk an accusation of state aid," the source said.
Poste Italiane's conditions will likely anger other Alitalia shareholders, notably Italy's top two banks Intesa Sanpaolo and UniCredit. They are already carrying the burden of restructuring large parts of the airline's debts.
Intesa and UniCredit are both the airline's creditors and among its key shareholders after repeatedly coming to Alitalia's rescue, partially under pressure from a government that was unwilling to let its flagship carrier collapse.
Poste, the banks and Alitalia have declined to comment.
A Poste board meeting on the issue is scheduled for Tuesday. Alitalia's shareholders are expected to vote on the 200 million euro capital increase on Friday.