UPDATE 2-Turkey's Akbank says systems back online after technical disruption

(Recasts with systems back online)

ISTANBUL, March 27 (Reuters) - Turkey’s Akbank said on Monday its systems were back online following technical problems that sources said prevented transactions for several hours at the country’s third-largest listed lender.

The bank said in a statement its systems were functioning properly. It did not give any information about the nature of the glitch. The bank had earlier described the problem as “temporary disruptions” to its intra-bank systems.

Banking sources told Reuters that the lender was unable to process transactions for several hours starting on Monday morning. This included transactions at ATMs, online, at branches, over mobile phone and at point-of-sale machines, one of the sources said.

Akbank has more than 15 million clients and a network that includes 4,200 cash machines and more than 460,000 point-of-sale terminals, according to its 2016 annual report.

The bank was targeted in December by hackers via the SWIFT global money transfer system in an attack it said had not compromised customer data but would cost it up to $4 million.

Shares of Akbank were down 0.67 percent at 8.83 lira by 1256 GMT, compared with a 0.61 percent decline in the Istanbul stock exchange’s index of banking stocks. (Additonal reporting by Nevzat Devranoglu; Writing by Humeyra Pamuk; Editing by David Dolan)