One third of suspects detained as alleged members of the terrorist group ISIS in Turkey since 2013 are foreigners, according to police sources.

The police officials, who spoke on condition of anonymity, said a total of 2,545 suspects were detained in anti-terror operations against ISIS; of those, 810 were foreign nationals.

Turkish security forces detained 230 suspects in 2013; 78 were put behind bars and, of those, 12 were foreigners, the police sources said.

In 2014, the number of ISIS members detained in operations across the country was 615: This included 240 foreigners; 87 of the total were jailed, and, of those, 21 were foreigners.

In 2015, a total of 1,700 suspected ISIS members were detained, and this figure included 492 suspects who were foreign nationals. Of the total, 419 were sent to prison including 95 foreigners.

The officials did not reveal any details about which countries the foreign nationals came from.

During the operations, arms and ammunition were seized: 19 long-barreled arms, 170 hand grenades, 51 hand-made explosives, 98 pistols, 84 rifles, 341 kilograms (751 pounds) of explosives, and 18,091 cartridges.

Among the arms were 42 sharp objects, and 50 explosive belts.

The officials also revealed that the ISIS group has not claimed responsibility for a number of attacks in Turkey. Police, however suspect that some bomb attacks were carried out by the group in the country.

The manhunt against ISIS members escalated after a ISIS suicide bombing killed 33 people in southeastern Şanlıurfa province on July 20.

Another blast killed more than 100 people in Ankara on Oct. 10.