A roadside blast killed three Pakistani paramilitary soldiers and wounded two on Saturday in a tribal region near the Afghan border, a military spokesman said.
The blast hit the soldiers on patrol 20 km (12 miles) east of Miranshah, the main town in the North Waziristan region, where Taliban and al Qaeda militants have been active.
"Soldiers were on a foot petrol when hit by an improvised device near a military checkpoint. It killed three of them," said military spokesman Major-General Waheed Arshad.
The attack came four days after an apparent missile attack killed 33 militants at a training camp in the region. Military officials said 23 of the dead were of Arab origin.
Intelligence officials said the missiles were possibly fired by US forces in Afghanistan. The Pakistani military denied any missiles had been fired and said the militants were killed in an explosion while making bombs.
Many Taliban and foreign al Qaeda militants fled to North Waziristan after US-led forces toppled Afghanistan's Taliban regime in 2001.
Afghan and US military say the militants direct their intensified insurgency in Afghanistan, and plot violence elsewhere, from sanctuaries on the Pakistani side of the border, including in North Waziristan.
Last September, the government struck a peace deal in North Waziristan aimed at marginalising foreign militants but critics said the pact had created a sanctuary for militants.
Nevertheless, the level of violence in North Waziristan has fallen sharply since then, and militant attacks on Pakistani troops have been rare.