People gather outside the Greek state television (ERT) headquarters in Athens June 11, 2013. [Agencies]

"Public broadcasting can't shut down," said Yannis Maniatis, a senior official of the Socialist PASOK party. "A three-way coalition doesn't work with 'faits accomplis'."

At the protest rally, opposition leader Alexis Tsipras called the closure "a coup, not only against ERT workers but against the Greek people", and accused the government of the "historic responsibility of gagging state TV".

The decision was made by ministerial decree, meaning that it could be implemented without reference to parliament.

"Journalism is being persecuted. We won't allow the voice of Greece to be silenced," said George Savvidis, the chief of journalists' labour union POESY.

Kedikoglou said ERT's staff would be encouraged to apply for jobs in a relaunched broadcaster, but did not spell out what this would look like.

European Broadcasting Union President Jean Paul Philippot wrote to Samaras urging him to reverse the decision.

"National broadcasters are more important than ever at times of national difficulty," he wrote.

Inspectors from the "troika" of lenders - the European Union, International Monetary Fund and European Central Bank - arrived in Athens on Monday for their latest inspection of Greece's progress in saving money under the bailout programme.

PASOK linked ERT's closure with a demand by the troika for 2,000 layoffs in the state sector by August, and called for an immediate meeting of party leaders.

"PASOK is in favour of brave, substantial state reforms," it said. "It is, however, against fleeting and dangerous moves that are aimed to impress."

Before the failure of the DEPA sale, Greece had been enjoying unexpected optimism from investors, who had pushed down bond yields and spurred talk of a recovery, a year after Greece almost crashed out of the euro zone. ($1 = 0.7533 euros)