Greece's coalition government on Thursday failed to agree on a new package of cuts demanded by international creditors, while a group of demonstrating police officers clashed with guards outside the prime minister's office where the meeting was held.

"Negotiations are continuing...nothing has been finalised yet," said Democratic Left leader Fotis Kouvelis, the junior partner of Greece's three-party coalition following the three-hour meeting.

When asked when he thought a final agreement would be reached on a package of cuts, Greek Finance Minister Yannis Stournaras said: "I do not know. I think it will take a few more days."

Greece is about 2 billion euros (2.6 billion dollars) short of the 11.5-billion-euro total that its lenders, the European Commission, the European Central Bank and the International Monetary Fund (IMF), collectively known as the troika, want.

Both the socialist PASOK and Democratic Left are opposed to axing workers in the public sector. A new meeting of coalition leaders is been scheduled for next week.

Another issue at dispute is a two-year increase in the retirement age to 67 demanded by the troika.

The plan also includes a new round of wage and pension cuts as well as cuts to disability and other welfare benefits which are expected to spark more demonstrations.

Minor scuffles broke out when a group of 30 police officers, coast guard and firefighters insisted on handing over a petition to the prime minister during the coalition talks.

Guards outside the building used pepper spray to push them back.

On Thursday, workers of Athens' metro, rail and tram networks launched a 24-hour strike and workers at the main ports of Piraeus and Thessaloniki walked off the job for 12 hours.

Judges and state hospital doctors also began protests this week, forcing hospitals to operate with emergency staff while tax employees are due to strike on Friday.

The work stoppages come ahead of a nationwide strike on 26 September.

A report from the troika expected by the end of September or early October is essential to secure Greece's next tranche of aid worth 31.5-billion-euro. Without it, Greece would be forced to default on its public debt.