Suspected Tamil Tiger rebels killed four police in a mine ambush in Sri Lanka's restive east today in the latest in a series of attacks on the military.
Tamil Tigers stand guard in the rebel-controlled area of Batticaloa
The attack comes as Norway's special peace envoy is visiting Sri Lanka to meet the Liberation Tigers of Tamil Eelam and the government amid diplomatic efforts to coax the rebels to resume peace talks they pulled out of indefinitely.
In the capital Colombo, police cordoned off the heart of the business district, citing an unspecified security threat, and stopped cars from approaching the World Trade Centre - home to the stock exchange, banks, companies from textiles to media and the government peace secretariat.
More than 270 people have been killed since February in what truce monitors and the Tigers say is now a "low-intensity war", including more than 20 security forces personnel and civilians in the past week.
Artillery, mortar exchanges and firefights are now common near forward defence lines in the north and east - where the rebels want to carve out a separate homeland for ethnic Tamils.
Many residents fear a return to a two-decade civil war that killed more than 64,000 people before a 2002 truce.
Diplomats say the European Union is poised to ban the Tamil Tigers as a terrorist organisation this month after a series of attacks on the military.