(Adds Banco Popolare's capital gain in 2013)
BRUSSELS, Feb 28 (Reuters) - The European Commission is looking into an Italian decree hiking the value of the central Bank of Italy's share capital to see if it amounts to state aid to banks, an EU spokesman said on Friday.
In November, Italy's government increased the value of the Bank of Italy's share capital to 7.5 billion euros ($10.3 billion) from 156,000 euros - a level that had not been changed since the 1930s.
The decree became law last month, allowing lenders that own a stake in the central bank to include a capital gain from the revaluation of their own holding in their 2013 accounts.
Banco Popolare, which was the first big Italian lender to report 2013 results, said on Friday the revaluation lifted its 2013 results by 48 million euros.
The boost will be a lot more sizeable for Intesa Sanpaolo and Unicredit, the two biggest shareholders in the central bank with stakes of 42 percent and 22 percent respectively.
Intesa is likely to book a gross capital gain of 2.5 billion euros, while UniCredit will have a 1.38 billion euro benefit, according to analyst estimates.
The European Commission sent a letter to Italian authorities earlier this month to ask for information about the revaluation.
"The Commission has asked Italian authorities for information about the decree-law of 30 November 2013 introducing changes to the capital of and share holdings in the Bank of Italy, in order to assess whether it could contain state aid to certain banks," European Commission Spokesman Antoine Colombani said on Friday.
The move has been hotly contested by some opposition parties which have criticised it as a sell-off of publicly owned assets to the banking sector but the Commission said its letter was "an autonomous initiative" unconnected with any outside action.
"This is simply a request for more information which of course does not prejudge in any way the substance of our assessment," Colombani said.
A source who had seen the EU's letter to Italy described its content to Reuters, saying it was dated Feb. 19 and that it asked for an assessment of the decree and whether it involved a transfer that could constitute state aid to commercial banks.
The governor of the Bank of Italy Ignazio Visco said earlier this month that the revaluation could boost the core capital - the highest quality capital according to Basel III rules - of Italian banks only from 2015 if the Bank of Italy allows it. ($1 = 0.7309 euros) (Reporting by Francesco Guarascio and Stefano Bernabei, writing by Naomi O'Leary and Francesca Landini; Editing by Toby Chopra)