Colombo - The heads of state of eight South Asian nations opened a two day regional summit in the Sri Lanka capital of Colombo on Saturday where issues ranging from environment to poverty are being discussed.

The event is being held under tight security after the government rejecting a truce declared by the Tamil rebels of the Liberation of Tigers of Tamil Eelam (LTTE).

Sri Lankan President Mahinda Rajapaksa opening the event called for regional co-operation in combating terrorism and stability in the region.

"There are not good terrorists and bad terrorists. We need to eliminate terrorism," Rajapaksa said.

Indian Prime Minister Manmohan Singh, Pakistani Prime Minister Yousaf Raza Gillani, Maldives President Abdul Gayoom, Bangladesh Chief Advisor Fakhruddin Ahmed, Nepalese Prime Minister Girija Prasad Koirala, Bhutan Prime Minister Jigme Thinley and Afghan President Hamid Karzai are attending the summit.

The Afghan president speaking immediately after President Rajapaksa said that of the many challenges the region faces terrorism was the biggest.

The summit in Colombo came as government troops continued their military operations in the northern part of the country aimed at recapturing more rebel held areas.

At least 11 soldiers and nine rebels were killed in fighting in the north on Friday, military spokesman Brigadier Udaya Nanayakkara said.

He said casualties were reported close to the Mallawvi area, 320 kilometres north of the capital following a direct confrontation between the two sides.

But, the pro-rebel Tamilnet website said that at least 30 soldiers had been killed in the clashes, a claim denied by the army.

The Defence Ministry on Friday said they had crossed the border of the Kilinochchi district, 290 kilometres north of the capital, after a fierce round of fighting.

Tamil rebels are now confined to two northern districts with the other being Mullaitivu, but troops crossed the border of that district earlier.

The rebels consider Kilinochchi as their stronghold and have set up their political office and peace secretariat.

The miliary has vowed to recapture the north before the end of the year. (dpa)