ATHENS, Greece — Greek Prime Minister Alexis Tsipras vowed to impose a new round of austerity measures in the next few weeks, but said the country would demand a debt relief deal from bailout lenders by Christmas.

“We are not coming as beggars or as the poor relative, but with our heads held high and with dignity, as representatives of a people that suffered so much,” Tsipras said Thursday, speaking at a congress of his left-wing Syriza party.

Greece has been surviving on bailout loans from other eurozone countries and the International Monetary Fund since 2010. But with a battered economy, its national debt is set to reach a whopping 315 billion euro ($347.5 billion) this year, or 179 percent of gross domestic product.

Athens wants swift action on lenders’ promises to provide longer maturities and a smoother repayment schedule.

“Telling us to get on with our homework and ‘we’ll see’ is no longer acceptable to us,” Tsipras said. “This delay in specifying measures needed for debt relief … has no, absolutely no, justification.”

Creditors are committed to improving terms for Greece, but the IMF and lead eurozone lender Germany are at odds over the urgency. Several eurozone members argue that Greece already has generous repayment terms and has delayed instituting vital structural reforms.

IMF and European debt inspectors are due back in Athens this month to press Greece on slashing government protection for distressed mortgage holders and workers at unprofitable companies — measures they argue are crucial to restart the economy after years of decline and stagnation.

Tsipras’ government argues that implementing more tough measures without debt relief would stifle the country’s recovery.

In a letter Thursday to EU Finance Commissioner Pierre Moscovici, 36 lawmakers from Greece’s Syriza party and allied European parties urged the European Union to press eurozone lenders on the debt issue.

“Any further delays regarding the beginning of a concrete and conclusive dialogue on debt relief could have devastating results on the Greek economy and counteract even the modest decrease of unemployment and poverty levels,” the letter said.

In Athens, Greek Economy Minister George Stathakis told parliament that without relief the national debt would be “not viable” in 2017 even if the government meets ambitious budget targets.

“We are at a key moment, because the debt sustainability calculation depends on strong assumptions,” Stathakis said. “It needs to be sorted out by Christmas. Otherwise it won’t work.”

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