* MPS top shareholder races to sell up to 15 pct stake
* Creditors divided over who should be repaid first
MILAN, March 1 (Reuters) - A row among creditors over how to share the proceeds from the planned sale of a 15 percent stake in Italy's No.3 bank is delaying the process and risks scuppering a potentially lucrative deal, sources close to the situation said.
The banking foundation that owns 49 percent of Banca Monte dei Paschi di Siena is in a hurry to sell a stake of up to 15 percent to repay part of the 1.1 billion euro debt it ran up to retain control of the Siena-based lender.
The foundation's 12 creditors have set a March 15 deadline for it to come up with a credible debt-cutting plan and have reacted coldly so far to the foundation's request for more time.
But the contracts the creditors have struck with the foundation - Fondazione Monte dei Paschi di Siena - differ, leaving some at a disadvantage in the event of a sale, one of the sources said on Thursday.
On top of that, the creditors need to decide whether to unblock the shares they hold as guarantee for their loans.
"The foundation is ready to sell the stake to give creditors their money back by taking the historical step of lowering its holding," said the source, who declined to be identified.
"But it is important that all the creditors make an effort to align their interests. There should not be a situation in which some could do an arbitrage."
The lion's share of the foundation's debt - around 600 million euros - is owed to a group of 11 domestic and international banks led by JPMorgan Chase & Co.
Separately, Swiss bank Credit Suisse is owed around 300 million euros while Italian merchant bank Mediobanca , which also acts as adviser to the foundation in the stake sale, is owed around 190 million euros.
Mediobanca is also owed a smaller portion as it is one of the creditors in the pool led by JP Morgan.
Further complicating the issue is the fact that some of the debt owed to Credit Suisse and Mediobanca is structured in the form of a derivative, two banking sources told Reuters.
"Each bank has different rights based on different contracts," said one of the sources.
Another source said: "The creditors' front is not united."
Talks to find an agreement between the banks are under way, but the foundation fears that reaching a deal could take time, with the March 15 deadline looming ever closer.
The foundation urged creditors on Wednesday to quickly unblock the shares it gave them as guarantee for their loans so it can proceed with the sale - although no firm offer from one or more buyers appears to have emerged so far.
"The foundation is confident that such agreement can be reached quickly to allow a positive outcome and avoid possible economic damage," it said.
However, in another statement on Thursday the foundation said it had not been given the green light from the creditors as there was no consensus among them on how to share the proceeds.
Three sources familiar with the situation said earlier this week the foundation was in talks with domestic investors to quickly sell an 8 percent stake to soothe the creditors.
The sources said the creditor banks already hold a stake of around 35 percent in the lender in the form of loan guarantees but at least some of them were unlikely to give them back to the foundation without a firm commitment from a buyer. (Reporting by Lisa Jucca, Silvia Aloisi, Stefano Bernabei; Editing by Mark Potter)