LONDON, May 25 (Reuters) - Intesa Sanpaolo ISP.MI has formally launched a process to syndicate the loan it provided to fund the purchase of a 19.5 percent stake in Russian energy giant Rosneft ROSN.MM by Glencore GLEN.L and a Qatari sovereign wealth fund, according to a banking source familiar with the matter.

Intesa provided a 5.2 billion euro ($5.83 billion) loan to Glencore and the Qatar Investment Authority late last year, but is now trying to spread its risk.

The head of Intesa's Russian business, Antonio Fallico, said in February that it was speaking with 14 banks about syndicating the loan, with the aim being to choose two or three to take on 2.5-3 billion euros of the debt.

A spokesman for Intesa declined to comment. ($1 = 0.8919 euros)

(Reporting by Dmitry Zhdannikov; Writing by Rachel Armstrong; editing by Simon Jessop) ((rachel.armstrong@thomsonreuters.com; +44 207 5423365; Reuters Messaging: rachel.armstrong.thomsonreuters.com@reuters.net))