The United Nations has confirmed that at least 19 students were killed by a bomb in eastern Sri Lanka. Hours later, another blast shook Sri Lanka's capital, killing seven people and injuring at least 17 more.

Aid officials say they dispatched investigators to the village in rebel-held territory when it was reported that bombs had been dropped on a orphanage.

U.N. spokesperson Orla Clinton says the agency is still gathering information about the incident, in collaboration with international cease-fire monitors form the Sri Lanka Monitoring Mission.

The orphanage was evacuated before recent hostilities erupted, but Clinton says it was being used by another group of young people.

"What we know at the moment is that these seem to have been students between 16-and-18, A-Level students, from the Kilinochi and Mullativu area, who were on a two-day training course in first aid," she said.

Investigators say it appears that the facility was bombed by "Kfir" jets, used by the Sri Lankan Air force.

"And apparently, four Kfirs, according to SLMM [the Sri Lanka Monitoring Mission], dropped bombs on the area, the center where they were," added Clinton.

The incident was first reported on a pro-rebel Web page, Tamilnet, which accused the government of deliberately dropping bombs on the facility. It lists the number killed at more than 60.

Sri Lankan military officials have denied responsibility for the incident.

The head of Sri Lanka's Peace Secretariat, Palitha Kohona, warned that the rebels may be trying to distract attention from battlefield losses.

"Now, when they are getting beaten back, they have started, as usual, and this fits into a pattern, a campaign of disinformation and trying to turn the tide by appealing to the heartstrings of the public," said Kohona.

The government and Tamil Tiger Rebels have been engaged in nearly three weeks of clashes. The violence threatens to plunge the country back into civil war, which first began in 1983, when the rebels demanded independence for the ethnic Tamil minority.

Meanwhile, seven people were killed in the capital Colombo, in a blast directed at the Pakistani ambassador.

Some officials have said a Claymore mine was detonated beneath his motorcade, while others say a three-wheeler taxi had been packed with explosives. 

Officials blame the attack on the Tamil Tigers, who may be angry that Pakistan supplies arms to the Sri Lankan government. The ambassador escaped serious injury. The rebel group is a State Department designated terrorist organization.