Organizers of this Sunday's Tokyo Marathon have promised increased security following the slaying of two Japanese hostages by the Islamic State group.

"We have held anti-terrorism drills and have worked closely with the police agency so we are confident of delivering a safe race," said race president Koji Sakurai.

About 30,000 runners are expected to take part in the race through the streets of Tokyo. Police will be among those runners as part of new security measures.

Islamist militants threatened Japanese people everywhere after the slaying of two Japanese hostages last month.

The Tokyo race is one the World Marathon Majors along with Boston, Chicago, London, Berlin and New York.

The Boston Marathon in 2013 was the target of a terrorist attack that killed three people.