The victims, almost all off-duty soldiers, were travelling through the northern district of Vavuniya, close to the frontline with the rebels' mini-state, when the bomb went off.
"Our first information was that 14 people were killed on the spot and several others were wounded," a police official in Vavuniya said.
"The military has told us that the figure is 10 soldiers killed and eight wounded."
"The bus was carrying unarmed army personnel who were going on leave," the defence ministry said in a statement.
"The injured have been rushed to the Anuradhapura General Hospital.
"
The convoy was travelling from the northwestern town of Mannar, a key government base and also the scene of fighting in recent days, when it was hit.
"We suspect that the bomb was placed on a parked vehicle and someone may have detonated it using a remote-controlled device," the police official said.
"As the convoy passed, the blast went off.
"
The four paramilitary policemen were killed earlier Tue