* Piraeus says certain investors to take up 10 pct of rights issue
* Alpha, Piraeus shareholders approve bond issues (Adds quotes, Alpha shareholders meeting, details)
By Lefteris Papadimas and George Georgiopoulos
ATHENS, Jan 31 (Reuters) - Greek bank Piraeus is confident it will be able to sell at least 10 percent of a planned share offering to the market, its chairman said on Thursday, ensuring the bank avoids falling into state hands.
Battered by the debt crisis and six years of recession, the country's four big banks - National, Eurobank , Alpha and Piraeus - are to be recapitalised with 27.5 billion euros ($37 billion) of state aid but must raise a small part from the market to avoid being nationalised.
Piraeus's capital need has been assessed by the central bank at 7.3 billion euros, of which up to 2 billion will come from contingent convertible bonds, or so-called CoCos, leaving about 5.3 billion to be raised via shares.
The country's second-largest lender by assets, after taking over part of ATE bank, is the first of the country's four major lenders to say it will have no problem meeting the required target under their planned recapitalisation.
"We are certain, based on the indications we have, that we will reach 10 percent," Piraeus chairman Michalis Sallas told a shareholder meeting, which also approved a contingent convertible bond issue of up to 2 billion euros.
The comment came days after rival Eurobank said terms offered under the recapitalisation scheme were not attractive enough and urged stronger incentives for private investors to take part in share offerings.
The CoCo issues will be solely taken up by a state bank support fund, the Hellenic Financial Stability Fund (HFSF), which has been set up to recapitalise the sector and wind down banks that authorities have deemed non-viable.
HFSF will subscribe to most of the capital to be raised through rights issues but, to stay privately run, the four big banks must raise at least 10 percent from private investors.
The banks must complete their share offerings by the end of April, but the lenders are lobbying for more time and executives at the HFSF support fund have also acknowledged the timeframe to be tight.
"If there was an extension (of the deadline for share issues) by one to two months it would help banks," another senior Piraeus executive told reporters, declining to be named.
"It will be a pity if there is no extension now that we see interest by serious foreign institutional investors."
At its shareholder meeting, Piraeus also signalled growing optimism for the country's banks since fears of a Greek bankruptcy and exit from the euro receded.
Sallas said Greek banks would manage to regain capital market access this year, a view also expressed by Eurobank's deputy chief executive in comments to Reuters earlier this week.
"I believe that in the summer, banks will be able to return to markets," Sallas said.
At a separate meeting, shareholders of rival Alpha Bank also gave the green light for a contingent convertible bond issue of up to 2 billion euros. ($1=0.7370 euros) (Editing by Deepa Babington and Mike Nesbit)