ATHENS (AFP) - Greece's new anti-austerity government submitted a list of reform proposals to Brussels on Monday in a bid to secure a four-month extension to its lifeline debt bailout, a European source said.

Details of the measures were not immediately known, but if they fail to win the approval of Greece's EU creditors, the country's safety net will collapse on Saturday leaving the government at risk of running out of cash, a run on banks and even a eurozone exit.

But hard left Prime Minister Alexis Tsipras, who swept to power in elections last month, could also face an angry backlash from voters if he fails to deliver on promises to ease the pain of ordinary Greeks after years of recession and painful austerity cuts.

In the latest in a series of dramatic showdowns over Greece's 240 billion euro (S$370 billion) bailout, flamboyant new Finance Minister Yanis Varoufakis secured the extension from his 18 fellow eurozone partners in Brussels on Friday.

The tentative agreement boosted global markets as fears of a "Grexit" or eurozone exit - which could have highly damaging wider ramifications - eased, and stocks mostly rose again on Monday in Asia and Europe.

The deal however came with the demand that Athens provide by Monday a list of measures to quash concerns, not least in powerhouse Germany, that Greece might backtrack on its commitments to cut spending and pass root-and-branch reforms.

"Europe has some breathing space, nothing more, and certainly not a resolution," German Foreign Minister Frank-Walter Steinmeier told the Bild daily on Monday.

"The fundamentals - namely assistance in exchange for reform - must remain the same."

REALITY BITES

Tsipras, 40, and his Syriza party have vowed to end the "humiliation" and "vicious circle" of the spending cuts demanded by Greece's creditors in return for two massive bailouts since 2010.

His election victory sent shockwaves through Europe, particularly in Germany, whose Chancellor Angela Merkel fears that reneging on austerity might catch on elsewhere and bring the eurozone debt crisis back with a vengeance.

Tsipras plans to use the next four months to draw up a new reform package that puts the country - where one in four people is out of work - on a fairer road to recovery after years of recession, spending cuts and state job losses.

But the tough negotiating stance of Germany and other eurozone countries has obliged the former student radical and his tieless foreign minister Varoufakis, 53, to give ground.

Athens pledged to refrain from one-sided measures that could compromise fiscal targets and had to abandon plans to tap some 11 billion euros in leftover European bank support funds.

UniCredit economist Eric Nielsen called it a "complete political surrender to the world of reality", saying that it was clear that Europe has "drawn the line in the sand".

Tsipras insisted at the weekend that his coalition government had achieved an "important negotiating success" which "cancels out austerity".

But cracks were already beginning to show.

"There can be no compromise... between a slave and a conqueror, the only solution is freedom," said one of Syriza's most respected members, 92-year-old wartime resistance hero Manolis Glezos.

"I wish to apologise to the Greek people for taking part in this illusion," Glezos said.

TAX HIT LIST

The European Commission, which together with the European Central Bank and the International Monetary Fund form the "troika" of Greece's creditors, has not said formally that it has received any list from Athens.

Once it does, and assuming the measures get the green light, the extension can go ahead - pending approval from some European countries' parliaments.

But if the proposals are not approved, it will be back to the drawing board for Greece, which is struggling under a 320-billion-euro debt mountain.

"The chance of policy mistakes, political volatility and implementation risks remains quite high, and may rise," said Daniele Antonucci, economist at Morgan Stanley.

Minister of state Nikos Pappas told television channel Mega on Sunday the new measures were aimed at making "the Greek civil service more effective and to combat tax evasion".

According to Germany's Bild, this will include a 7.3 billion-euro tax hit list targeting the fortunes of the super-rich, back taxes on companies and a crackdown on fuel and cigarette smuggling.

"If the list of reforms is not agreed, this agreement is dead," Varoufakis said on Friday.