(Adds details on state aid request, Deutsche comment)
MILAN Jan 17 (Reuters) - Banca Monte dei Paschi di Siena , Italy's third-biggest bank, said on Thursday it was carrying out checks over past structured finance operations that are in its portfolio and could still have an impact on its accounts.
The bank said in a statement that it was assessing the possible effect of such transactions so as to take action as soon as possible and in any case by the time it publishes its 2012 accounts, which should be sometime in March.
"The assessment, which has not been completed yet, relates to the legal, financial, accounting and management aspects of the operations," the statement said.
In November, Monte Paschi asked for an extra 500 million euros ($668 million) in state aid, saying it needed more money to offset a possible hit from a renegotiation of past structured transactions.
It did not explain which structured deals it was referring to.
Thursday's statement came after a report by Bloomberg said Deutsche Bank had designed a derivative contract for Monte dei Paschi in December 2008 that helped it mitigate a 367-million euro loss from an older derivative contract, also with Deutsche Bank.
Annual reports show that Monte dei Paschi liquidated the financial structure with Deutsche Bank, dubbed Santorini, in June 2009.
A Monte dei Paschi spokesman declined to comment on whether the Santorini transaction was one of the trades that forced it to raise its state aid request by 500 million euros to a total of 3.9 billion euros.
Asked about the Bloomberg report, Deutsche Bank said: "In 2008 we entered into a financing transaction with our client, Banca Monte dei Paschi. The transaction was subject to our rigorous internal approval processes and also received the requisite approvals of the client who was independently advised."
Monte dei Paschi requested state aid last June after failing to meet tougher capital requirements set by the European Banking Authority (EBA).
The need for state help was based on a capital shortfall of 3.3 billion euros, largely because it was forced to cover for potential losses on its 25-billion euro Italian government bond portfolio at the height of the euro zone crisis.
Under the bailout plan agreed to with the Rome government and the European Commission, the Tuscan lender will issue 3.9 billion euros of bonds to the Italian treasury by March. ($1 = 0.7486 euros) (Reporting by Silvia Aloisi and Stefano Bernabei; addiitonal reporting by Edward Taylor in Frankfurt and Antonella Ciancio; Editing by M.D. Golan)