(Updates with no damage)

COLOMBO, Sept 10 (Reuters) - Sri Lankan authorities were on Wednesday investigating a blast that struck a railway line just south of the capital Colombo, which caused no damage or injury, the military said.

"There was an explosion underneath the railway track. There was no damage to the track, no damage to property and no injuries," military spokesman Brigadier Udaya Nanayakkara said.

The blast took place in Mount Lavinia, a favourite weekend spot for city residents just south of the capital.

Investigations into the blast were underway and Nanayakkara said it was too early to say who was responsible.

The rebel Tamil Tigers, fighting the government since 1983 for a separate homeland for the ethnic minority Tamil people, have repeatedly used bombs in Colombo.

The rebels could not immediately be reached for comment.

On Monday night, an explosion wounded at least nine people in Colombo and police blamed criminals for the attack. (Reporting by Ranga Sirilal; Editing by Janet Lawrence)

AlertNet news is provided by