(Photo: AP)

ISTANBUL, Dec. 26 (Xinhua) -- Turkish police on Thursday detained 20 foreign nationals and a Turkish citizen in Istanbul over their suspected links to the Islamic State (IS) militant group.

Police launched operations simultaneously in 48 locations across the city to capture the suspects, who were believed to have been planning terror attacks, the state-run Anadolu Agency reported.

Some organizational documents and digital materials were also seized during the raids.

The nationalities of the foreign suspects were not immediately clear.

IS militants have been blamed for a series of deadly attacks in Turkey over the past years, in which more than 300 people were killed.