Two Turkish journalists went on trial in Istanbul Friday facing possible life terms on controversial espionage charges, with the court immediately barring the public from a case seen as a test of press freedom under President Recep Tayyip Erdogan.

Can Dundar, editor-in-chief of leading opposition daily Cumhuriyet, and Erdem Gul, his Ankara bureau chief, are charged with espionage and revealing state secrets over a story accusing the government of seeking to illicitly deliver arms to rebels in Syria.

The U.N. human rights chief voiced alarm Thursday over an EU-Turkey deal to slow migrant arrivals to Europe, saying it had legal flaws and contradictions that could have global repercussions.

Zeid Ra'ad Al Hussein said in a statement there was "a contradiction at the heart of the agreement," and voiced deep concern at the "arbitrary detention of refugees and migrants."

Turkey has detained a Japanese citizen in the south of the country on suspicion of seeking to cross the border into Syria to join Islamic State (IS) jihadists, the Dogan news agency said on Wednesday.

The young man aged 24, named as M.M., was detained late on Tuesday in the Nizip district of the southern city of Gaziantep, close to the Syrian border.

The Netherlands evacuated and closed its Turkish consulate in Istanbul on Wednesday because of a possible terror threat, the Dutch foreign ministry said.

The move comes after the latest attack on Saturday that killed three Israelis and an Iranian in a busy Istanbul shopping hub, blamed by the Turkish authorities on a jihadist with links to the Islamic State group.

A Syrian refugee who was trapped for over a year at Istanbul's main airport after being refused entry to Turkey has been transferred to a detention center, Amnesty International said Tuesday.

On Saturday, Fadi Mansour, who is reported to be in his twenties, left the windowless "problematic passengers room" at Ataturk airport where he was being held for a migrant detention center in Istanbul, Amnesty said.

President Recep Tayyip Erdogan on Monday urged Turks to stand tall against "one of the biggest waves of terrorism" in their history, as police hunt three alleged jihadists suspected of planning further suicide attacks.

In a combative speech in Istanbul Erdogan drew on the "grandeur of the Ottoman Empire" in promising to crush the Islamic State radicals and Kurdish rebels behind a string of bombings that have killed over 200 people since July.

A Turkish Islamic State recruit, Mehmet Ozturk, carried out the suicide bombing that killed four foreigners on a major shopping artery in Istanbul, Interior Minister Efken Ala said Sunday.

"The attacker has been formally identified. He is linked to the terrorist organization Daesh," Ala told a press conference, using an alternative name for IS.

EU leaders and Turkey's prime minister approved a controversial deal to curb the huge flow of asylum seekers to Europe, with all migrants arriving in Greece from Sunday to be sent back.

Friday's deal makes Turkey Europe's bulwark against its biggest migration crisis since World War II, but comes at a heavy price and amid criticism from rights groups.

Cyprus President Nicos Anastasiades said Thursday that a compromise was possible on an EU-Turkey deal on the migration crisis at a summit in Brussels, days after threatening to block the accord over his country's tense relations with Turkey.

"There are obstacles, but I do hope that during the deliberations that will follow at the European Council, there is going to be a compromise," Anastasiades told reporters at a meeting of center-right leaders ahead of the summit.

European Union leaders warned hard work was needed at a summit on Thursday to seal a deal with Turkey to curb the migration crisis, despite signs that key hold-out Cyprus is ready to compromise.

Several expressed concerns about the proposed accord, under which all migrants landing in Greece would be sent back to Turkey which has been seeking EU membership for decades.