Bratislava (AFP) - Eurogroup head Jeroen Dijsselbloem warned Athens on Friday to swiftly deliver on overdue reforms as its massive bailout programme fell off track triggering fears of a new row with Greece.

Leftist-led Greece is struggling to deliver on fresh reforms that are needed to unlock a further 2.8 billion euros ($3 billion) in bailout loans and more crucially, launch negotiations on debt relief later in the year.

"The pressure is back on. We really need some progress. The summer is over, pack up the camping gear, get back to work," Dijsselbloem, who leads the group of 19 finance ministers from the eurozone, told reporters in Bratislava.

Athens has committed to deliver on the reforms by the end of the month. They include the long delayed launch of a massive privatisation fund and reforms in the highly sensitive energy sector.

The EU's Economic Affairs commissioner Pierre Moscovici said Athens must deliver on 15 reforms, with only two of those achieved so far.

"It's not a secret ... that there is a lot to be done to complete these reforms," he said after the ministers discussed Greece's bailout.

"The Greek authorities must know that we are waiting for them, for the matter of trust and efficiency," he said.

Greece's creditors are mostly concerned with staffing picks proposed by Athens to run the privatisation fund, which are seen as too inexperienced or too politically linked to the ruling Syriza party, a European source told AFP.

- 'Still time' -

The influential German Finance Minister, Wolfgang Schaeuble, said Greece still had a short period of time to get back in line on its 86 billion euro bailout programme, agreed amid much bitterness in July 2015.

"They have to do this until the end of September, so there is still time for Greece," Schaeuble said.

Left unaddressed at the talks was the part played by the IMF, which was key to Greece's three bailouts but is now holding off until the eurozone ministers commit to debt relief for Athens.

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"The IMF is in a very constructive mode and I'm very happy about that", Dijsselbloem said, adding that the Washington-based fund would take a decision on its role by the end of the year.

Mujtaba Rahman of the Eurasia risk assessment group warned that the tensions risked boiling over early next year "when the government needs cash and its ECB obligations are once again around the corner."

Delays by Athens make it easier "for creditors to hide their differences and blame Greece. As such it pushes off the need for Germany and the IMF to come to a deal over debt relief," he added.

The eurozone ministers met in the Slovak capital as Greek Prime Minister Alexis Tsipras, an anti-austerity champion, hosted a mini-summit between the European Union's seven Mediterranean states in Athens.

Schaeuble belittled the summit as a political meeting of "socialist party leaders", even though non-left leaders attended.

"And when socialist party leaders meet, most of the time, nothing intelligent comes out of it," he added.