Pakistani officials say a suspected missile strike by a U.S. drone aircraft has killed up to 10 militants in a tribal region near the Afghan border.

The attack late Tuesday in North Waziristan followed a similar strike a day earlier that killed five people in the same region.

U.S. unmanned aircraft are believed to have fired more than 40 missiles at suspected al-Qaida and Taliban strongholds in northwest Pakistan in recent months.  American officials rarely discuss the missile strikes, which Pakistan has publicly criticized as counterproductive and a violation of its sovereignty. 

Meanwhile, the Pakistani military says its forces killed 24 militants during an operation in the Khyber region targeting the Taliban-affiliated group Lashkar-e-Islam.

The offensive was launched last week following a suicide bombing at a border checkpoint that killed at least 21 people, most of them police.

The military has reported killing more than 100 militants in the region over the past week, but the toll cannot be independently verified.

Earlier Tuesday, officials in northwestern Pakistan said militant gunfire killed four high-school students in Orakzai tribal region, a stronghold of the Pakistani Taliban's new chief, Hakimullah Mehsud.

Some local officials suggest the students were targeted because they were minority Shi'ite Muslims, but a Pakistani television report (ARY News) says the young students were caught in an exchange of gunfire between two rival groups.

In other violence, police officials say gunmen in southwestern Pakistan set fire to eight container trucks carrying supplies for U.S. and NATO troops in neighboring Afghanistan.

Some information for this report was provided by AFP, AP and Reuters.