By Simon Gardner

COLOMBO, Feb 4 (Reuters) - A caller claiming to be from a little known Sri Lankan rebel group warned of bomb attacks on Independence Day celebrations on Monday due to take place in the capital Colombo within hours.

Sri Lanka's military said the group, Ellalan Forces, was a codename used by Tamil Tiger rebels behind attacks in the capital including one on Sunday when 11 people were killed in a rail station bombing.

President Mahinda Rajapaksa is due to oversee an exhibition of military might in the capital on Monday morning, when tanks and thousands of troops will parade in the city, fighter jets will fly overhead and attack boats sail by to mark the 60th anniversary of independence from colonial ruler Britain.

The military is already on high alert after a series of bombings blamed on the Tigers in recent weeks, including Sunday's suicide bombing at the island's main train station in the capital which killed 11 and wounded 92.

"Please, be careful. There are going to be bombs in Colombo in some places," the anonymous caller told Reuters, saying he represented 'Ellalan Forces' -- a little known group the military identified as a codename for Tiger fighters operating in the capital.

"In some places we have fixed bombs to target Independence Day celebrations.

The caller was unknown to Reuters, and hung up when asked if he was linked to the Liberation Tigers of Tamil Eelam. The Tigers were not immediately reachable for comment.

"Ellalan forces ... are those operating in Colombo," said military spokesman Brigadier Udaya Nanayakkara. "It's the Tigers."

Troops have cut off roads near the parade site along a promenade by the Indian Ocean, and mobile telephone subscribers have been advised all SMS services will be cut for several hours, a measure seen aimed at hindering any efforts to coordinate attacks.

Fighting between the Sri Lankan military and the LTTE rebels has intensified since the government scrapped a six-year-old ceasefire last month, saying the rebels were using it to rebuild and re-arm and were not sincere about talking peace.

President Mahinda Rajapaksa's government also banished Nordic truce monitors, and has been widely criticised by the international community for abandoning the truce pact and taking the war to the rebels through military offensives following a series of Tiger attacks.

Hundreds of people have been reported killed in recent weeks and analysts say both sides tend to exaggerate enemy losses in a propaganda war that runs parallel to a conflict that has killed an estimated 70,000 people since 1983. (Editing by Sanjeev Miglani)

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