Top Afghan and U.S generals have visited Pakistan amid heightened security concerns following last week's Taliban-led school massacre in Peshawar.

Pakistan's army chief General Raheel Sharif addressed anti-terrorism efforts with Afghan General Shir Mohammad Karimi and U.S General John Campbell, commander of U.S and NATO forces in Afghanistan.

A statement by the International Security Assistance Force said Tuesday's meeting in Islamabad focused on military coordination "on both sides of the border."

The restive frontier between Afghanistan and Pakistan is seen as a haven for several militant groups, including the Taliban, which claimed responsibility for the Peshawar school siege that killed nearly 150 students and teachers.

General Sharif traveled to Afghanistan a day after the attack to address transnational threats with Campbell and Afghan President Ashraf Ghani.

Pakistan is engaged in a months-long offensive against rebels along the border. The Taliban cited the army's actions since June in the North Waziristan tribal district as the motive for the school assault.

Authorities have made an unknown number of arrests linked to the attack and an investigation is ongoing.

The country also responded by reinstating capital punishment. Pakistan announced on Monday the planned executions of about 500 Islamist terrorists, with six militants having been hanged since Friday.

Regional officials also have threatened to deport nearly three million Afghan refugees, most from Khyber Pakhtunkhwa province. Following the school attack in the province's capital of Peshawar, leaders gave Islamabad one month to determine the fate of the area's undocumented residents.