ISTANBUL (Reuters) - A Turkish court took the trial of two prominent journalists charged with espionage behind closed doors on Friday and accepted President Tayyip Erdogan as a complainant, in a case which has drawn international condemnation.

Can Dundar, editor-in-chief of Cumhuriyet, and Erdem Gul, 49, the newspaper’s Ankara bureau chief, stand accused of trying to topple the government with the publication last May of video purporting to show Turkey’s state intelligence agency helping to truck weapons to Syria in 2014.

Erdogan, who has cast the newspaper’s coverage as part of an attempt to undermine Turkey’s global standing, has vowed Dundar will “pay a heavy price”. The two journalists could face life in prison if convicted.

Anti-government chants rang out as the decision to take their trial behind closed doors was announced in the Istanbul courtroom, packed with journalists, opposition politicians, rights groups, relatives and diplomats from several nations.

“We will try you in stadiums” shouted some of the protesters. “You will get lost in the depths of that palace” said others, in reference to Erdogan’s vast new palace complex in Ankara, as security guards ushered them out.

The trial was later adjourned to April 1 after opposition lawmakers refused to leave, two of the lawmakers told Reuters.

The prosecutor argued for a confidential trial because some evidence involved state secrets. Lawyers for the journalists argued that evidence could be read in closed session while the rest of the trial should remain open.

Erdogan has acknowledged that the trucks, which were stopped by gendarmerie and police officers en route to the Syrian border, belonged to the MIT intelligence agency and said they were carrying aid to Turkmens in Syria. Turkmen fighters are battling both President Bashar al-Assad and Islamic State.

But he has said that prosecutors had no authority to order the trucks be searched and that they were part of what he calls a “parallel state” run by his ally-turned-foe Fethullah Gulen, a United States-based Islamic cleric who Erdogan says is bent on discrediting him and the Turkish government.

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The prosecutors have denied those allegations, while Gulen has denied plotting against the government.

A 473-page indictment says the editors aided a “terrorist” network led by Gulen, which they deny.

Ahead of the trial, Dundar said he would use the hearings to refocus attention on the story that landed him in the dock.

“We are not defendants, we are witnesses,” he told Reuters in an interview at his office last week, promising to show the footage in court despite a ban.

“We will lay out all of the illegalities and make this a political prosecution ... The state was caught in a criminal act and it is doing all that it can to cover it up.”

“TEST CASE”

The trial comes as Turkey deflects criticism from the European Union and rights groups that say it is bridling a once-vibrant press. EU enlargement chief Johannes Hahn described the trial on his Twitter account as a “test case for press freedom and rule of law in Turkey”.

Dundar and Gul spent 92 days in jail, almost half of it in solitary confinement, before the constitutional court ruled last month that pre-trial detention was unfounded because the charges stemmed from their journalism.

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Both were subsequently released pending trial, though Erdogan said he did not respect the ruling.

“Elsewhere in the world (Dundar and Gul) would be lauded for their efforts to dig into this issue,” said Nina Ognianova of the Committee to Protect Journalists (CPJ).

“They have done their jobs as investigative journalists, serving the public interest in pursuing a story that is significant not just for the country, but the region,” she said, describing the trial as part of a “massive crackdown on press freedom”.

Authorities this month seized control of Zaman, Turkey’s top-selling newspaper, on charges it funded Gulen’s network. A few weeks earlier the pro-Kurdish IMC channel was pulled off the air over allegations of “spreading terrorist propaganda”.

Zaman’s editor-in-chief said at the time the seizure was because of its criticism of government policies. IMC denied any ties with terrorist networks and said its closure was also a political decision.

Dundar took the helm at Cumhuriyet, which has a circulation of 52,000, last year and worked to overhaul the staunchly secular 92-year-old daily into a left-leaning outlet with more readers. A new investigative reporting unit he set up unearthed the footage of the purported arms shipment.