ISTANBUL (Reuters) - Turkish police detained 51 suspected members of Islamic State in Istanbul on Friday, anti-terrorist police said.

The suspects were believed to be planning to travel back to conflict zones in Syria, they said in a statement, adding that all those detained were foreign nationals.

Islamic State has carried out numerous bombings across Turkey in recent years, including an attack on a nightclub in Istanbul on Jan. 1, 2017, in which 39 people were killed and a bombing in the city’s historic heart that killed 12 in 2016.

Turkish operations against Islamic State suspects intensified at the end of last year ahead of the anniversary of the nightclub shooting.