Greece will not make a June 5 repayment to the International Monetary Fund if there is no prospect of an aid-for-reforms deal with its international creditors soon, the spokesman for the ruling Syriza party's lawmakers said on Wednesday.

The payment of 300 million euros ($335 million) is the first of four this month totaling 1.6 billion euros from a country that depends on foreign aid to stay afloat.

Greece owes a total of about 320 billion euros, of which about 65 percent to euro zone governments and the IMF, and about 8.7 percent to the European Central Bank.

On Tuesday, Greece's creditors drafted the broad outlines of an agreement to put to the leftist government in Athens in a bid to conclude four months of negotiations and release aid before the country runs out of money.

"If there is no prospect of a deal by Friday or Monday, I don't know by when exactly, we will not pay," Nikos Filis told Mega TV.

Greek Prime Minister Alexis Tsipras heads to Brussels on Wednesday to meet European Commission President Jean-Claude Juncker.

Tsipras, who has vowed not to surrender to more austerity, tried to pre-empt a take-it-or-leave-it offer by the creditors, sending what he called a comprehensive reform proposal to Brussels on Monday.

A Syriza European Parliament lawmaker said the government's 47-page proposal would be a good basis for discussion at a meeting of euro zone deputy finance ministers in the so-called EuroWorking Group which would convene on Wednesday.

"If the lenders show the same realism that the Greek government and the Greek Prime Minister is showing, then we can have a deal in principle by Friday or before Friday," Dimitris Papadimoulis told Antenna TV.

He said this could turn into a comprehensive deal next week.

"But right now there is no deal, there is convergence," he said.

Deputy social security minister Dimitris Stratoulis said a deal with lenders would have to respect the government's commitments.

"The agreement will either be compatible with Syriza's policy pledges, the core, or there will not be a deal," he told Antenna TV.