"This proves again the Port of Colombo is one of the safest ports in the world," Mangala Samaraweera, the ports minister, said during a visit to the site.
The military said they arrested three people from one boat, but the fate of others aboard the remaining craft was unknown.
Tamil Tiger attacks
LTTE conducted a suicide attack against the southern naval port of Galle in October, killing a sailor and a civilian and damaging several naval craft.
Fighters entered the Colombo port in April 1996, damaging foreign ships with rocket-propelled grenades, but their vessel was destroyed by security forces before they caused serious damage.
Since then, authorities have tightened security and banned fishing near ports to prevent attackers mingling among fishermen.
In July 2001, the Tigers attacked the island’s international airport near Colombo, destroying six civilian jets and blowing up more than a dozen military aircraft parked at an adjoining air base.
|Government troops captured the main LTTE |
base of Vakarai in the island's east [AFP]
Police said there was confusion on Saturday because authorities had also planned security manoeuvres, so many believed that the firing was part of a drill.
The incident came after the military captured the main LTTE base of Vakarai in the island's east and increased operations against Tiger forces in the region.
More than 3,800 people have been killed in the past year despite a truce since February 2002. Norwegian-backed peace talks collapsed in October.
The Tamil separatist conflict, led by the LTTE, has claimed more than 60,000 lives in the past 35 years and political attempts to resolve the conflict have failed.