Tokyo held its first missile evacuation drill on Monday with volunteers taking cover in subway stations and other underground spaces that would double as shelters for the Japanese capital in the event of a North Korean missile strike.

The choreographed evacuations at a fair ground and park ringing the Tokyo Dome baseball stadium involved around 300 volunteers.

Small groups of protesters scuffled with police as they demonstrated against what they criticised as a war game that fanned public fear.

While hope grows that North Korea's participation in next month's Winter Olympics in South Korea may help defuse tension in the region, Japan is escalating efforts to prepare its citizens for a possible war.

Tokyo believes the threat posed by Pyongyang's ballistic missile and nuclear weapons development is deepening.