The blast hit a bus transporting troops and police in the Jaffna peninsula, military spokesman Prasad Samarasinghe said.
"An officer and a soldier were killed in the blast," Samarasinghe said. "Two officers, eight soldiers and two policemen escaped with injuries.
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He said three civilians were also wounded in the attack, which occurred close to a vegetable market.
The attack came a day after a civilian was killed in a similar mine blast in the same area.
A total of 13 people were also wounded in separate bomb explosions in Sri Lanka on Tuesday.
Despite a February 2002 truce, clashes have escalated between the two sides with more than 850 people killed in a fresh wave of violence since December.
Sri Lanka's peace broker Norway has been trying to arrange direct talks between the militant Liberation Tigers of Tamil Eelam and the Sri Lankan government to halt the violence.
Sweden is also bidding to rescue Sri Lanka's crumbling 2002 ceasefire.
More than 60,000 people have been kille