Greek Prime Minister Alexis Tsipras is to request an emergency European summit on his country's troubled bailout program, after talks with creditors again failed to achieve a breakthrough.

Greek officials say Tsipras will call European Union Council President Donald Tusk later Wednesday to proposal the meeting of leaders from European countries that use the euro currency.

Athens' stock index is down nearly 4 percent after the new setback Tuesday in the talks between Greece and representatives of its European partners and the International Monetary Fund.

Greece's finance ministry says there is agreement on creditor-demanded austerity measures worth 3 percent of GDP — or 5.4 billion euros — by 2018. But disagreements remain over how to guarantee that an extra 3.6 billion euros in savings will be implemented if deemed necessary.