Pakistan's military says "heavy fire" from across the Afghan border has killed seven soldiers deployed at a post near Afghanistan.

In a statement to media, the military says the Pakistani post came under fire on Tuesday morning in the South Waziristan tribal region. It didn't say who was behind the attack but authorities have in the past blamed Pakistani militants for such cross-border assaults.

Pakistan has deployed thousands of troops in the country's tribal regions to rout local and foreign militants hiding there.

The military has carried out several operations in the country's tribal regions bordering Afghanistan over the past 10 years, but violence has continued.