Pakistani officials say mortars fired from Afghanistan have hit a paramilitary post in Pakistan's tribal region, killing four soldiers.

The latest incident of cross-border violence occurred Tuesday in the Angoor Adda area of South Waziristan.

Local security officials say at least two other paramilitary soldiers were wounded. Afghan officials did not immediately comment on the report.

Tensions along the Afghan-Pakistani border have risen in recent weeks.

Pakistan says militants allegedly coming from Afghan bases have killed more than 55 soldiers in recent attacks. Pakistan has protested the cross-border attacks and called on Afghan and NATO forces do more to crack down on insurgents.

Afghanistan accuses Pakistan of intentionally firing hundreds of rockets into its territory, killing at least 36 Afghan civilians. Pakistan says its security forces may have fired a few accidental rounds into Afghanistan while pursuing militants.

Taliban and al-Qaida-linked militants have save havens on both sides of the porous Afghan-Pakistani border.

On Tuesday, Pakistani President Asif Ali Zardari traveled to Kabul and offered condolences to Afghan President Hamid Karzai on the recent assassination of his half-brother, Ahmad Wali Karzai.