Lightning has killed four soldiers and wounded 59 others during military training in north central Sri Lanka, the military said.

"When troops were gathered for the training at the training camp in Katukaleyawa in Polonnaruwa, all of a sudden lightning struck the place and four soldiers were killed and 59 injured," military spokesman Brigadier Udaya Nanayakkara said.

The military said fighting between government troops and Tamil Tiger rebels, engaged in a 25-year-old civil war, in the northern districts of Vavuniya, Mannar and Jaffna on Tuesday killed 12 Tamil Tiger rebels and two soldiers.

The Liberation Tigers of Tamil Eelam, seeking to create an independent state in north and east Sri Lanka, were not available to comment on the latest fighting.

The Government and rebels usually trade death toll claims that are rarely possible to independently verify.

Analysts say the military has the upper hand in the latest phase of the long-running war given superior air power, strength of numbers and swathes of terrain captured in the island's east. But they still see no clear winner on the horizon.

An estimated 70,000 people have died since the civil war began in 1983.