ANKARA (Reuters) - Turkish authorities on Wednesday detained 35 suspected members of Islamic State in raids across Istanbul, broadcaster Haberturk said.

Police carried out simultaneous raids in 41 locations across the city and collected several documents linked to the jihadist group, it said.

The group has been blamed for at least half a dozen attacks on civilian targets in Turkey over the past 18 months, prompting the authorities to intensify efforts to break up its suspected networks.

Thirty-nine people, mainly foreigners, were killed on New Year’s Day when an Islamic State militant opened fire inside the Reina nightclub Istanbul. Islamic State said the attack was revenge for Turkish military involvement in Syria.

NATO member Turkey is part of the U.S.-led coalition against Islamic State and launched an incursion into Syria in August to drive the jihadist group and Kurdish militia fighters away from its borders.