ATHENS -- Greek Prime Minister Alexis Tsipras is seeking an emergency EU summit to unlock the immediate payment of further bailout aid to Athens, the Greek national news agency AMNA reported Wednesday, citing government sources.

The initiative follows the latest impasse in negotiations between the Greek government and envoys of the country's international creditors.

Greek cabinet ministers were optimistic over the past few weeks that by May 1, Greece would have reached an agreement with its lenders on the next set of measures, which would clear the way for the release of the next payment and the start of talks on debt relief.

However, the first review of the third bailout program since 2010 Athens clinched last summer has not been concluded despite marathon negotiations.

The same government sources, according to the news agency, put the blame for the new deadlock mainly on the International Monetary Fund for delaying the talks and insisting on a preemptive legislation to allow contingency measures of some 3 billion euros (3.4 billion US dollars) to be automatically enacted if Athens fails to meet a 3.5-percent primary surplus target in 2018.

The Greek government counterproposed the establishment of a "reliable balancing mechanism," arguing that under the Greek constitution, all laws passed through the Greek parliament have immediate effect, therefore preemptive legislation was unconstitutional.

On Wednesday the Athens Stock Exchange General Index opened with a 4.3-percent decline with banks suffering the heaviest losses, while several Greek newspapers were debating in editorials on the prime minister's options.

Political analysts in Athens said the possibilities of new snap general elections or a referendum cannot be ruled out if the government and the creditors don't strike a deal soon which can be ratified by the parliament.