Imphal, Dec 15 (IANS): A 28-year-old youth was killed and five others were injured when unidentified militants triggered a bomb blast here Monday, police said.

"Naresh Sahani, a betel leaf seller, died on the spot and five others were seriously wounded when militants exploded a bomb in the heart of Imphal city's Mahatma Gandhi avenue," a police official said.

The injured people were taken to the Regional Institute of Medical Science and hospital. The condition of three of them is stated to be critical.

Sahani and three of the injured belong to Bihar and the others are from Manipur.

Security forces led by inspector general of police Clay Khongsai and deputy inspector general of police I.K. Muivah have launched a combing operation to nab the militants behind the blasts.

"We are yet to identify the group which triggered the blast," Khongsai told reporters adding that an improvised explosive device was used in the explosion.

Manipur Chief Minister O. Ibobi Singh strongly condemned the blast.

After visiting the injured persons at RIMS hospital, the chief minister, along with Deputy Chief Minister Gaikhangam, assured that the state government would extend all necessary financial help to the injured people and the victim's family.

No militant group has claimed responsibility for the blast yet.

A similar explosion occurred during Durga Puja celebrations at a nearby area in Imphal Oct 1 in which a dozen people were hurt. A 10-year-old boy was killed in a blast in Manipur Nov 29 a day ahead of Prime Minister Narendra Modi's visit.