Norwegian truce monitors have warned that Tamil Tigers acquiring "air assets" could "destabilise" the island's security as well as that of India.

The 60-member Sri Lanka [Images] Monitoring Mission said the Liberation Tigers of Tamil Eelam had an airstrip in the island's north, though it had not seen any rebel aircraft in action.

The mission also warned that any move by government forces to bomb it could lead to resumption of war.

"We have seen the airstrip air while flying in a Sri Lankan military helicopter on May 4 last year," SLMM chief Hagrup Haukland told the Foreign Correspondents' Association of Sri Lanka on Thursday night.

However, he said the monitors were unable to investigate Sri Lankan government complaints that the rebels had at least two light aircraft because the Tigers did not allow them access to the area.

"Not allowing us access itself is a violation of the ceasefire agreement. An air capability-- the air assets-- mean a hell of a lot in this sort of warfare," Haukland said.

He added it could undermine not only Sri Lanka's security but also that of India and the entire region.

"It not only destabilises Sri Lanka's security, but India's security as well."

"If the Tigers fly, it will be a violation of Sri Lankan airspace and also of international law because the air space is a matter only for the Sri Lankan government," he said.

"If the (Sri Lankan) air force bombs the air strip, then it will be war."