* Central bank estimates losses at 664 mln euros in 2012
* Governor had last week given figure of 606 mln
* Gives no reason for increase, says risk of more losses
* Abanka Vipa says fails to get fresh capital (Rewrites first paragraph, adds Abanka's failed attempt to hike capital, writes through)
By Marja Novak
LJUBLJANA, Feb 19 (Reuters) - Slovenia's central bank has given a sharply increased estimate of losses among its ailing banks, which are at the heart of speculation that the country may need an international bailout.
The Bank of Slovenia said the banks, most of them state-owned, made a combined 2012 pretax loss of 664 million euros ($886 million), just days after central bank governor Marko Kranjec estimated their losses at 606 million.
The comments came as the country's third-largest bank Abanka Vipa said its attempt to raise up to 90 million euros in a share issue had failed because of lack of investor interest, underscoring the sector's problems.
The Bank of Slovenia did not explain why its latest loss estimate was significantly higher than given by its governor last week, but said on Tuesday there was a risk of a further worsening of the banks' portfolios and more losses in 2013.
It said provisions taken by the banks had risen 23 percent in 2012 to 1.5 billion euros.
The country's lenders are nursing some 7 billion euros of bad loans, equaling 20 percent of GDP, which last year prompted speculation that Slovenia could become the latest euro zone member heading for a bailout.
On top of that, the country has a government crisis that may stall crucial reforms and result in early elections. The ruling conservative coalition has lost its majority in parliament over a corruption scandal involving Prime Minister Janez Jansa.
Jansa has denied any wrongdoing and pledged to hold on to the helm of the minority government. But analysts expect a snap election later this year, the second in as many years.
In a statement after its regular bi-monthly board meeting, the central bank called for government policies to focus on boosting the economy.
"All economic policies have to be focused on establishing conditions for economic growth that would ease the process of companies' financial restructuring and improve conditions for bank financing," the bank said.
In 2011 Slovenian banks made a joint pretax loss of 539 million euros and Kranjec told Reuters in January the Slovenian banking system could end 2013 with a combined total loss for a fourth straight year.
Elsewhere partly state owned Abanka Vipa said it would hold another attempt to increase its capital strength by issuing new shares to the value of 90 million euros, but gave no timing of the issue.
It said the share price would be priced at a minimum 1 euro each, compared with a price of 4.2 euros for the previous unsuccessful issue.
($1 = 0.7490 euros) (Editing by Stephen Nisbet and David Holmes)