TOKYO (Reuters) - The Tokyo police are investigating the possibility that a Japanese student tried to travel to Syria to join the Islamic State of Iraq and Syria (ISIS), Chief Cabinet Secretary Yoshihide Suga said on Tuesday, as the United States carries out air strikes on militant targets.

Mr Suga did not elaborate, but the Asahi Shimbun daily said the police questioned a 26-year-old man, taking a leave of absence from Hokkaido University in north Japan, about plans to go to Syria to join ISIS as a fighter. "I am aware the 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," Mr 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 Asahi said the 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 ISIS, although Mr Suga then said the government had not confirmed the information.

The United Nations 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 ISIS.

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