Sri Lankan troops launched their first deliberate advance on Tamil Tiger rebels since a 2002 ceasefire today, moving to secure a rebel-held water supply as government jets bombed suspected groups of Tiger fighters.
More than 800 people have been killed so far this year, with the closing of a water channel from an eastern rebel-held area to government-held farms prompting a surge in violence in recent days including air and artillery strikes.
Ground forces were sent in to secure irrigation for the ethnic majority Sinhalese farms in the area, south of the northeastern port of Trincomalee.
The government said troops then came under mortar fire from the Liberation Tigers of Tamil Eelam (LTTE) but no-one was hurt.
The army said the advance was continuing but that soldiers were having to pick their way through minefields. The rest of the island appeared quiet.
In recent months, the mainstream Tigers and breakaway ex-rebels the Karuna group have raided each other's positions in the east, and a clash between the rebels and army earlier in July killed 12. But there has been little serious infantry action.
Both the government and the Tigers claim control over the site of the reservoir, which lies in an area where the border between the foes is ill-defined. However the ground reality is that the Tigers control the area, military sources said.
The Tigers, want a separate ethnic Tamil homeland and pulled out of peace talks in April, deny shutting the sluice gate themselves and say it was done by local Tamil civilians angry at the government. The Tigers said they had no details on any new clashes.
Earlier, local Tiger political leader S. Elilan said the rebels had not yet observed any movement, but warned the army against entering their territory. "If the military intend to advance into our area then they will see the consequences in a very strong manner," he said.
Diplomats fear that without new talks and with world attention focused on Lebanon, Sri Lanka could spiral back into a full-scale two decade-old civil war that has already killed more than 65,000 people on an island also hit by the 2004 tsunami.