By Renee Maltezou

ATHENS (Reuters) - Greece will support a declaration marking the European Union's 60th birthday but needs the bloc's backing against International Monetary Fund demands on labor reforms, Greek Prime Minister Alexis Tsipras said ahead of an EU Summit in Rome.

In a letter addressed to EU Council President Donald Tusk and European Commission President Jean-Claude Juncker, Tsipras called for a clear statement on Greece's place given that talks over a key bailout review have hit a snag again.

"We intend to support the Rome Declaration, a document which moves in a positive direction," Tsipras said.

"Nevertheless, in order to be able to celebrate these achievements, it has to be made clear, on an official level, whether they apply also to Greece. Whether, in other words, the European (agreement) is valid for all member states without exception, or for all except Greece."

The comment reflected Greece's belief that it is being treated differently from others in its bailout dealings with euro zone partners.

Greece had threatened not to sign the Rome declaration, demanding a clearer commitment protecting workers' rights -- an issue on which it is at odds with its international lenders who demand more reforms in return for new loans.

The disagreements among Athens, the EU and the IMF -- which has yet to decide whether it will participate in the country's current bailout -- have delayed a crucial bailout review. Greece faces big debt repayments in July.

Greek ministers have been negotiating with lenders' representatives in Brussels on pension cuts, energy and labor reforms, including freeing up mass layoffs and collective bargaining.

But the Brussels talks ended inconclusively despite initial hopes for a deal on key issues which would allow EU/IMF mission chiefs to return to Athens soon for detailed deliberations. Negotiations were likely to continue via teleconference.

"The ministers are returning to Athens," a government official said, expressing optimism that open issues "would be sorted out within the day or in the coming days".

Athens agreed last month to adopt more measures to help convince the IMF to participate in its third, 86-billion euro bailout, as demanded by EU countries including Germany, which faces a national election later this year.

Another official said slashing the retail market share of state-controlled Public Power Corp. was also a thorny issue as lenders were pushing for the sale of power units, a move that Tsipras' Syriza party and unions have resisted.

Greece has cut pensions 12 times since it signed up to its first bailout in 2010. It has also reduced wages and implemented reforms to make its labor market more flexible and competitive.

A German finance ministry spokeswoman said on Friday that the completion of the review hinged on Athens which had to do more on pension and labor reforms.

Tsipras' leftist-led government came to power in 2015 promising to end austerity but signed up to a new bailout to keep the country in the euro zone. It was later re-elected on a mandate to protect workers' and pensioners' rights, but opinion polls show its popularity ratings sagging.

Tsipras said Greece had met its bailout terms on fiscal adjustments and implemented labor reforms, which were not in line with best practices in Europe.

"I ask for your support in order to protect, together, the right of Greece to return to the standards of the European social model," he said in the letter.

(Additional reporting by Lefteris Papadimas; Editing by Jeremy Gaunt)