Yusuf Polat was charged on Saturday with attempting to violently overthrow the constitutional order, the most serious charge so far laid against any of those detained over the Istanbul attacks.

Turkey's Anatolia news agency said that searches in a residence used by Polat uncovered material used in making the kind of bomb detonated at the Beth Israel synagogue

Deputy Istanbul Police Chief, Halil Yilmaz, said Polat had been to the Beth Israel site on the day of the bombing and gave the final order for the attack. 

Suicide bomber named

Meanwhile, the suicide bomber who detonated a truck bomb outside the offices of British-based banking giant HSBC in Istanbul, has been formally identified by DNA testing, Anatolia said on Sunday.

The man, whose remains were analysed at the Istanbul Forensic Medicine Institute and compared with the DNA of his relatives, was identified as Melvut Ugur, Anatolia reported.

The identification led to several arrests of the bomber's family members, it added.

Police have now identified four suicide bombers who detonated explosives-packed trucks at two Istanbul synagogues on 15 November, leaving 27 people dead, and at the British consulate and HSBC building on 20 November, claiming 30 lives.