Indonesia's anti-terrorism police have arrested four Turks suspected of being linked to the ISIS terrorist group, a spokesman said on Sunday. The elite Detachment 88 police squad arrested the men, along with three Indonesians, after tailing their car on Saturday in central Sulawesi district of Poso, a known hotbed for militant activity, Boy Rafli Amar told AFP. "They are Turkish," Amar said, confirming the arrest and adding that the men were being investigated for their connection to the dreaded ISIS. "We suspect they are linked and are investigating further," he said. Indonesia has long struggled with terrorism, but a successful clampdown in recent years has seen the end of major deadly attacks. Jakarta has estimated that dozens of Indonesians have traveled to Syria and Iraq to fight and President Susilo Bambang Yudhoyono said he was concerned about their return, adding that he had tasked agencies to oppose the spread of extremist ideology in the sprawling nation. Ronny Sompie, another police spokesman said two of the Indonesians arrested Saturday had fetched the foreigners "believed to be from an international terror group" from Makassar airport in South Sulawesi. "The four foreigners managed to flee to the mountains" before their capture, he said.