TOKYO – Tokyo police are investigating the possibility that a Japanese student tried to travel to Syria to join Islamic State, Chief Cabinet Secretary Yoshihide Suga said on Tuesday, as the United States carries out air strikes on militant targets.

Suga did not elaborate, but the Asahi Shimbun daily said police questioned a 26-year-old man, taking leave of absence from Hokkaido University in north Japan, about plans to go to Syria to join Islamic State as a fighter.

"I am aware police conducted a search based on the criminal law. But I would like to refrain from going into details because the matter is under investigation," Suga told a news conference.

"As a member of the international community, our country has a policy of actively taking steps to prevent terrorism."

The U.N. Security Council last month demanded that all states make it a serious criminal offence for their citizens to travel abroad to fight with militant groups, or to recruit and fund others to do so, a move sparked by the rise of Islamic State.

The Asahi said police confiscated the college student's passport and questioned a person who is related to a Tokyo book store where a help-wanted note for a job in Syria was posted.

Former Japanese air force chief Toshio Tamogami last month quoted a senior Israeli government official as saying that nine Japanese nationals had joined Islamic State, although Suga then said the government had not confirmed the information.

About 1,000 recruits from a vast region stretching from India to the Pacific may have joined Islamic State to fight in Syria or Iraq, the head of the U.S. Armed Forces' Pacific Command, Admiral Samuel Locklear, said last month.