Turkish authorities said on Friday that 42,888 illegal immigrants caught in Istanbul, the largest city in Turkey, are to be deported.

The illegal immigrants were captured in operations launched since July 12 and sent to repatriation centers for deportation, the Istanbul governor's office said in a written statement.

In addition, the security forces have also captured 6,416 Syrian refugees not registered in the city, noted the statement.

It said the Syrians were transferred to temporary accommodation centers in several provinces designated by the Interior Ministry.

In July, the governor's office ordered Syrian refugees who were registered somewhere else in Turkey to leave Istanbul and return to their places of registration by Aug. 20, which was later extended until Oct. 30.

There are a total of 1.06 million registered refugees in Istanbul, with 547,000 of them being Syrians, according to the authorities.