A major security forum scheduled to be held next month in Singapore has been canceled due to the coronavirus pandemic, its organizer said Thursday.

Prime Minister Yoshihide Suga had been expected to participate in the June 4-5 gathering, known as the Shangri-La Dialogue, sponsored annually by the International Institute for Strategic Studies, a British think tank. It would have been the first attendance by a Japanese leader in seven years.

The forum was expected to be an occasion for Suga to promote a free and open Indo-Pacific, a vision sought by Japan and the United States as China increases its maritime assertiveness in the region.

"Unfortunately the global COVID-19 situation has recently deteriorated, in part because of the rise of infectious new COVID variants," IISS said in a statement.

"In Singapore there has been a rise in local cases, the introduction of new restrictions, and the prospect of further tightening cannot be ruled out, all of which creates uncertainty," it said. "Taken together these various factors mean that holding an in-person Shangri-La Dialogue this year has become unviable."

The conference, which has been held in Singapore since 2002, was similarly canceled last year after pandemic forced many countries to restrict travel and shut their borders.

The event has provided a platform for ministers and top military officials for more than 40 countries, including the United States and China, to discuss major security challenges in the region.

The last time a Japanese prime minister attended the event was in 2014 when Shinzo Abe, Suga's predecessor, was in the post.