"Four people were killed on the spot and another died later," LTTE spokesman Rasiah Ilanthiriyan told AFP by telephone from Kilinochchi, 330 kilometres (206 miles) north of the capital.
"We see this as state terrorism and urge the international community to condemn it.
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The defence ministry said the airforce had carried out two separate air attacks inside rebel-held territory, but could not say if there was an attack just outside the Kilinochchi hospital.
"We have bombed a Sea Tiger base at Mannar (southwest of Kilinochchi) and a location about 10 kilometres southeast of Kilinochchi," defence ministry spokesman Prasad Samarasinghe said.
He said there were no details of casualties.
Asked if the airforce had bombed a location near the Kilinochchi hospital, Samarasinghe said he had no information about it.