Imphal, Sep 14 (IANS): Nine people - all migrant labourers from various parts of India - were killed and 20 others injured in a powerful bomb blast Friday in Manipur's Imphal West district, police said.

The powerful explosion took place around 7.45 p.m. at the busy Nagamapal area on the outskirts of Imphal.

"Altogether, nine migrant labourers have died and 20 others were injured when a powerful bomb planted inside the makeshift shed exploded," Manipur police chief M.K.Das told IANS.

Of the 20 injured people, who were taken to the Regional Institute of Medical Science (RIMS) here, Das said two of them are in critical condition.

He said all the victims of the blast were migrant labourers working employed by a Kolkata-based construction firm.

A security alert has been sounded and the blast site has been cordoned off

Das said preliminary reports suggested that the blast could have been triggered by an improvised explosive device (IED).

"A forensic team has started collecting evidence from the site of the blast. We would be able to know only tomorrow (Saturday) morning which rebel group is responsible for the blast," he said.

No arrests had been made so far, he added.

No rebel group has claimed responsibility for the blasts.

Earlier, troopers of the Assam Rifles patrolling along the Ukhrul-Imphal road in Imphal East district made a narrow escape when a powerful IED, planted on the roadside, exploded.

The incident occurred at around 10.30 a.m. near Khurai Popular High School at Khurai Thongam Leikai in Imphal East.

An auto-rickshaw driver was injured in the incident.

The outlawed Peoples Liberation Army (PLA), an armed wing of Revolutionary Peoples Front (RPF) had claimed responsibility for the morning blast.

There are an estimated 19 militant group active in Manipur, bordering Myanmar, with demands ranging from secession to greater autonomy.