ANKARA, March 5 (Xinhua) -- Turkish police have detained 12 suspects in Ankara as part of an investigation on Islamic State (IS), state-run Anadolu Agency reported on Monday.

According to report, Ankara counter-terrorist units detained the 12 suspects in raids across the city, after the Ankara prosecutors' office issued a detention warrants for 20 suspects on Monday.

It said that all the suspects are foreigners, without providing detail on their nationalities.

On Sunday evening, the U.S. Embassy to Turkey said it would be closed to public on Monday due to an unspecified security threat.

Turkey has suffered several bloody attacks blamed on IS militants since 2015. Turkish police have intensified operation against IS cells across the country.