Istanbul, January 14 (RHC)-- Turkish authorities have arrested five suspects in connection with a deadly bomb attack in the historic heart of the city of Istanbul that left 10 foreigners dead.

According to Prime Minister Ahmet Davutoglu, four suspects were arrested on Wednesday in relation to the attack. Turkish Interior Minister Efkan Ala said earlier in the day that one individual had been arrested on Tuesday evening, but did not explain the suspect's role in the attack.

The blast took place in the city’s Sultanahmet square, a major tourist attraction on Tuesday, with Ankara claiming that it was carried out by a Syrian identified as 28-year-old Nabil Fadli, who was a member of the Daesh Takfiri terror group and had recently entered Turkey from Syria.

"The investigation is continuing in a very intensive way," Ala told a news conference in Istanbul alongside his German counterpart Thomas de Maiziere. Elsewhere in his comments, Ala said the bomber had recently registered with Turkish immigration authorities, but was not on any list of known militant suspects.