Bullet train services between Tokyo and Osaka were partially suspended on Monday following an overnight derailment accident involving maintenance vehicles, the operator said.

Central Japan Railway Company said that services on the Tokaido Shinkansen Line could be suspended for all of Monday as restoration work is expected to continue until the evening, reports Xinhua news agency.

Trains were halted between Nagoya and Hamamatsu stations, while operations were resumed between Tokyo and Hamamatsu and Nagoya and Shin-Osaka with about two trains per hour on each of the lines, it added.

Major train stations were crowded with stranded passengers seeking to change their tickets and making inquiries to station staff as the incident took place when the summer vacation season just started in Japan, local media reported.

Central Japan Railway urged travellers to avoid affected stations until services are fully restored and to consider changing their travel plans.

According to the operator, a maintenance train that lays ballast, or small rocks under rail tracks, collided with a halted maintenance train on a section of the line between Toyohashi and Mikawa-Anjo stations in Aichi Prefecture shortly past 3:30 a.m. local time, derailing both trains and causing two workers to sustain no life-threatening injuries.

The Tokaido Shinkansen Line connects the cities of Tokyo, Yokohama, Nagoya, Kyoto and Osaka, which constitute Japan's three largest metropolitan areas.