Police announced on Thursday that five suspects allegedly acting as money couriers for the DAESH terrorist organization were detained in Istanbul on Tuesday.

The suspects, all foreigners whose names were not disclosed, are accused of transferring money sent to the group active in Syria and Iraq from overseas.

Police sources said the first suspect, captured in the city's Fatih district, has been under surveillance over suspicion of heading a small group working for the terrorist organization and arranging money transfers. The suspect has been frequently traveling to Iraq and Syria and was reportedly in close contact with top DAESH officials.

He was found in possession of nearly $100,000 when he was detained. Sources said he was planning to deliver it to DAESH members. In a second raid, at a textile workshop where the suspect frequented in Istanbul, four others were detained. All suspects remain in custody, as they are still being interrogated by police.

Along with facilitating the transfer of funds from other countries to DAESH, the suspects were charged with collecting funds for the terrorist organization in Turkey.

The operation comes one month after a major raid targeting DAESH members in the capital, Ankara. A total of 11 suspects accused of recruiting for DAESH were detained by police in those raids.

Turkey has detained 3,318 people as part of its efforts against DAESH and other terrorist organizations since they emerged in Syria a few years ago, and police have arrested 847 out of the 3,318 suspects, according to the Interior Ministry.

In Ankara, two would-be suicide bombers and a number of suspects accused of aiding them were detained in December before New Year's celebrations when they planned to strike.

DAESH was blamed for the suicide bombing on Jan. 12 in Istanbul's Sultanahmet Square that killed 11 German tourists.

Turkey is among the primary targets of the terrorist organization, which controls towns near the country's border with Syria, for its contribution to the campaign against DAESH.

In January, some 200 DAESH members in Syria were killed by artillery fire from the Turkish side in retaliation for the Sultanahmet bombing.