At least 20 Sri Lankan soldiers were killed and more than 100 wounded in fresh fighting with Liberation Tiger of Tamil Eelam rebels in the northern peninsula of Jaffna on Saturday, military sources said.

The 20 soldiers were killed in the first wave of attacks mounted by troops against Tiger positions along the de facto border in the Jaffna peninsula, the sources said.

The offensive, mounted from Kilali, Muhamalai and Nagarkovil was aimed at pushing back Tiger guns that threatened military installations and civilians in Jaffna, they said.

The Sri Lankan Air Force had the day before carried out intense aerial bombardment against Tiger positions in the southern part of the peninsula.

"The army has now advanced about a kilometre into territory previously occupied by the Tigers," an officer said.

"This means we have taken their first line of defence."

There was no word from the Tigers about the latest clashes or about the possible casualties on their side.

Meanwhile, the Sri Lanka [Images] navy on Saturday sent a troop carrier to ferry at least 800 people, who had been stranded in northern Jaffna, out of the peninsula.

"The navy undertook this humanitarian mission considering the plight of civilians in the Jaffna peninsula who are faced with irregular transport facilities," the defence ministry said in a statement.