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ISIS flagReuters

An Ankara court on Saturday remanded in custody pending trial two Turkish men suspected of belonging to ISIS and planning a double suicide bombing in the capital on New Year's Eve.

Musa Canoz, 28, and Adnan Yildirim, 40, who were detained in a raid on Wednesday, were placed under arrest on charges of "possessing explosive materials" and "membership of a terrorist organization", the Anatolia news agency reported.

They were sent to the Sincan prison in Ankara, it added. It was not clear when a trial may start.

Turkish officials said the pair were planning to strike an area in the center of the city that was expected to be packed with revelers on the night of December 31. In the end, the celebrations passed peacefully.

Turkey is on a high security alert after 103 people were killed on October 10 when two suicide bombers ripped through a crowd of peace activists in Ankara in the worst attack in modern Turkey's history.

The Hurriyet daily reported that the pair had left Ankara in 2013 to join up with ISIS forces in Syria, where they received bomb-making training.

They then crossed back into Turkey in September this year, renting an apartment in the Mamak district of Ankara where they were detained.

It said they had been given final instructions over the Internet by an ISIS handler, an Arab with the codename Ebu Enes, on the day they were detained.

A third suspect, named as Z.A., has been detained on suspicion of providing logistical and transport support, it added.

The suspected bombers are believed by investigators to have been acting on the orders of ISIS headquarters in their self-declared capital in Raqa, Syria, rather than independently, it added.

Long criticized by its allies for taking too soft a line against jihadists, Turkey is taking firmer action against ISIS on the border with Syria after being shaken by attacks on its soil and the Paris assaults on November 13.

AFP contributed to this report.