In a post on his personal Facebook page, SKAI news director Malelis accused Prime Minister Alexis Tsipras' government of attempting to silence its critics. "To the regime's various party dogs. You're not going to silence me, no matter what you do. No form of power ever did and neither will you. There's a huge difference between you and I. I've worked all my life, while you have been warming your party seats. You're wasting your time with threats. I don't bite it. Anyone with arguments here I am!" he said. The Journalists' Union of Athens Daily Papers said it had "called on our nine members to address the accusations" before its ethics board. Last week the union released a statement criticising the reporting from certain, unnamed, journalists. "Unfortunately, some colleagues mainly in television media, instead of following the imposed strict ethical rules, diverted to delinquent behaviour, substituting the journalistic function with undisguised propaganda."

A spokesman for the government-appointed independent media watchdog Greek National Council for Radio and Television said the council would also be launching "an investigation into the way these channels reported the referendum". He said the CEOs of the channel would likely have to account for their journalism. It was reported in Greek media on Monday that the Parliament may also consider sanctions against the channels. "It is the obligation of the Greek Parliament to protect the Greek Republic and… to take such measures to ensure violations of electoral legislation do not go unpunished," a parliamentary spokesman for Syriza told TVXS. Privately-owned media, who have generally urged a deal with EU creditors, have been heavily criticised by the government and the 'no' campaign. On Wednesday morning, Mr Tsipras told members of the European Parliament that local media had been "terrorising Greeks" into picking yes. Dimitris Kotaridis, a journalist with ANT1 and the treasurer of the ESIEA union, said the union's ethics committee had come under the control of Syriza affiliates and the move was "politically organised". He understood the committee had plans to expand the investigation up to 300 journalists - all of them from private TV and radio stations. The state-owned TV station ERT, which is generally pro-government, would escape scrutiny.

"It's totally stupid because they are investigating only those that were in favour of the yes… Even if you have said something in the past that wasn't politically correct or wasn't so in favour of Varoufakis, the former minster of finance, they are calling you, you have to apologise for that. It's purely political," he said. "I think it's very bad for journalists in Greece. We have been under heavy attack the past years. People have been getting beaten on the street. It's difficult for journalists to go to certain areas in Athens." Under Greek law, each party must be given exactly the same amount of time to present its case. It is standard practice for TV channels to be fined for their coverage. But Nikolas Vafiadis, the foreign editor of ANT1, told Farifax that the targeting of his colleague Maria Houki and other privately owned media was "politically motivated". "These are early signs of an authoritarianism that is developing here in Greece and I'm very much worried as a journalist with an open spirit that we are heading towards fanaticism," he said. He said channels may have pursued or favoured certain editorial angles, but that this was normal practice.

"Thank God we have pluralism in Greece. I think we are heading for new era of Stalinism." SKAI released a statement on Wednesday defending its reporters. It said: "All these actions have one purpose: the silencing of the 'other', any 'other' views and opinions, and to hide 'annoying' news reporting and the truth." On the day of the referendum, the minister of health Panayotis Kouroublis​ criticised the "black propaganda" of the Mega television channel, attacking in particular the reporting of Ms Tremi and Mr Pretenteris - both are among the nine under now investigation. At the post-referendum celebrations on Sunday evening in Athens' Syntagma Square revellers chanted "f--- journalists".