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* Greeks walk off job over new austerity
* Parliament expected to pass measures May 18
* Government 'brought disaster' say pensioners
ATHENS, May 17 (Reuters) - Thousands of Greeks walked off their jobs on Wednesday and marched through central Athens in an angry protest against continued austerity measures being demanded by international lenders in exchange for disbursing bailout funds.
There were isolated clashes with police, but the demonstration was generally peaceful.
The strike was called by the country's main public and private sector unions a day before Greece's parliament is due to vote on reforms that would help unlock the funds from the 86-billion-euro bailout, the country's third in seven years.
New austerity attached to the funds release include the 13th cut in pensions since 2010 and a reduction in tax-free allowances on income. They come after years of cuts that for a time threw the country into deep recession.
Unemployment is running at close to one in four and there is a 48 percent jobless rates among the youth.
A few domestic flights were grounded and public transport was disrupted throughout Athens. At least 15,000 people including pensioners, teachers, doctors and lawyers, marched to parliament as lawmakers debated the new measures.
Protesters held banners reading "No to austerity, yes to debt relief!" and "Bring back the conquered rights that you stole from us!". They chanted "They talk about losses and gains and we talk about human lives".
Some of the demonstrators expressed anger at the coalition government of Prime Minister Alexis Tsipras, whose leftist Syriza party came to power in 2015 promising to stop the cuts.
"They told us they would end austerity and tear apart the bailouts," said Paraskevi Tsouparopoulou, 62. "Instead they brought us disaster."
Clashes broke out outside parliament as the march ended.
Police fired teargas at a group of protesters hurling petrol bombs and firecrackers at them. A small group of demonstrators were seen firing projectiles at police with what appeared to be improvised devices. Others held hammers.
Greece has agreed to the further spending cuts to end a logjam in talks with its foreign lenders, the European Union and the International Monetary Fund, over its bailout progress.
Once the new measures are approved by Greek lawmakers -- as is expected -- euro zone finance ministers will then discuss the disbursement of the loans at the next scheduled Eurogroup meeting on May 22.
Athens needs the funds urgently to repay 7.5 billion euro ($8.18 billion) in debt maturing in July.
Tsipras and German Chancellor Angela Merkel agreed during a call on Wednesday morning that "a deal was feasible" by Monday, a government official said.
SAVINGS AND RELIEF
The new cuts are designed to produce savings worth 2 percent of gross domestic product and meet a target for a 3.5 percent of gross domestic product primary surplus - which excludes debt servicing costs.
If Greece outperforms those goals, it will activate a set of measures offsetting the impact of the additional austerity, including mainly lowering taxes.
Once approved, the Eurogroup has said it will consider some form of debt relief for Greece, which is still struggling under a debt mount amounting to 179 percent of gross domestic product.
When this may happen, however, is in contention between the Washington-based IMF and the euro zone.
Greece has needed three multi-billion bailouts since 2010 and additional belt-tightening is a contentious issue for Tsipras's leftist-led government, which now trails its conservative opponents in polls.
"We have been fooled. We believed in their promises," said Nikos Moustakas, 71, a retired mechanic who worked for 38 years. "They have lost me as a voter," he said.
Tsouparopoulou, the pensioner, was waiting in a queue for food handouts, a common feature in Greece where thousands have come to rely on charity. She held a bag with a loaf of bread, a packet of pasta and two eggs.
"Any other government would have at least given us a piece of bread." (Writing by Michele Kambas; Editing by Jeremy Gaunt)