Greece's Prime Minister Alexis Tsipras has told his government that creditors haven't yet accepted his country's proposals for a crucial bailout as he prepared for emergency talks in Brussels, Bloomberg news agency reports, citing a government official.

Tsipras on Wednesday is to meet with European Central Bank president Mario Draghi, International Monetary Fund chief Christine Lagarde and European Commission president Jean-Claude Juncker in an effort to reach a deal.

Before the meeting, he lashed out at objections raised by his country's creditors to the latest Greek reform proposals designed to unblock bailout funds, the Associated Press news agency reported.

Greece debt crisis: brinkmanship or bust?

The IMF has reportedly objected to Greece's latest proposals, saying they rely too heavily on tax increases rather than spending cuts, and risk hurting the economy.

A Greek official told the AP news agency that before departure, Tsipras spoke to his colleagues about "the insistence of certain institutions to not accept equivalent measures", meaning measures designed to generate the same amount of savings as those proposed by creditors.

The official quoted Tsipras as saying that "this strange stance can hide two possibilities. Either they don't want a deal, or they are serving particular interests in Greece."

The official spoke on condition of anonymity because of the sensitivity of the talks.

'Cautious optimism'

Eurozone leaders on Tuesday had expressed cautious optimism that a Greek bailout could be sealed this week after Greece offered economic reforms that creditors considered potentially acceptable at an emergency summit in Brussels.

Tsipras presented a proposal on Monday that was expected to be reviewed before Thursday when all 28 European Union leaders will meet to consider the offer.

Greece's proposals include higher taxes and welfare charges that EU leaders welcomed as a basis for a possible agreement to unlock frozen aid.

Greece and its creditors had exactly one week to go on Tuesday before Athens was due to repay the International Monetary Fund (IMF) around $1.7bn or face default and a possible exit from the EU.

The country is attempting to unlock the final 7.2bn euro ($8.1bn) tranche of its international bailout, which creditors have refused to release unless Greece agrees to more austerity measures.

Source: Al Jazeera and agencies