The government has no information to support the claim that several Japanese nationals may have joined the Islamic State group in Iraq and Syria, Chief Cabinet Secretary Yoshihide Suga said Friday.

"We, as the government of Japan, have yet to confirm such information," he told a news conference.

In a recent blog post about a trip he made to Israel, former Air Self-Defense Force chief Toshio Tamogami said he heard from Nissim Ben Shitrit, a former Israeli ambassador to Japan, that "nine Japanese have joined the Islamic State extremist group, along with British and other nationals."

A senior Foreign Ministry official said Tokyo is "checking with the Israeli side."

U.S. President Barack Obama said during a high-level U.N. meeting in New York on Wednesday that an estimated 15,000 foreigners, from more than 80 countries, have traveled to Syria in recent years to fight.

Also on Wednesday, the U.N. Security Council unanimously adopted a resolution saying member states should "prevent and suppress the recruiting, organizing, transporting or equipping" of fighters who travel to countries where extremists gather, as well as the financing of their travel or activities.