Twenty-three people, including women and children, were on Thursday injured in two separate blasts and an attack in Assam that were believed to be carried out by the banned United Liberation Front of Assam.

A powerful improvised explosive device hidden in a bicycle went off in the busy Athgaon area in Guwahati at about 1800 hours, injuring at least 20 people, Kamrup District (metro) Deputy Commissioner Avinash Joshi said.

"The ULFA was behind the blast," Joshi told PTI.

A grenade explosion in Gaurisagar area of Sibsagar district, believed to have carried out by ULFA militants injured two people. In another incident in the Beltola area of Guwahati, ULFA militants shot and seriously injured a businessman.

The attacks came a day after the Indian Olympic Association cleared the holding of the National Games in Guwahati from February 9 despite a call by ULFA to boycott the event.

Chief Minister Tarun Gogoi, who was in New Delhi, condemned the violence and issued instructions to police to nab those responsible for the attacks.

Ordering the tightening of security in and around Guwahati, Gogoi said his government will take stern steps against those indulging in subversive activities in the state.