At least three Pakistani soldiers were killed and four injured Tuesday when a mortar fired from Afghanistan hit their outpost in the north-western tribal area, security officials said, DPA reported.
The incident occurred in the Angoor Adda area of South Waziristan, one of seven districts where thousands of troops have been deployed since military operation against the militants in October 2009.
A security official said that at least six mortars were fired from across the border and one of them hit a post of the paramilitary Frontier Corps (FC), which is responsible for monitoring the cross-border movement of militants.
"The attack killed three soldiers and injured four others," he said, speaking on condition of anonymity.
The tension between Pakistan and Afghanistan has increased due to cross-border raids into Pakistan in recent weeks, and reliatory rocket fire by Pakistan. One cross-border raid in June in Upper Dir killed at least 30 Pakistani policemen.
In a separate incident, one Pakistani army major and eight militants were killed on Tuesday when dozens of militants attacked security forces in the Kurrum tribal district, where the army launched an operation against the Taliban two weeks ago, an intelligence official said.
Officials have said that nine solders and around 60 militants have been killed since the beginning of the operation.
Also Tuesday, a roadside bomb killed five tribesmen in the Shakai area of South Waziristan.
A local official said that they were part of a peace committee and were on their way to attend peace council meeting when their vehicle was hit.