PESHAWAR: A bomb resembling a toy killed at least six children Sunday in Speenmark village in the South Waziristan, officials said.

The bomb exploded while the children were playing with it in the tribal district.

"Six children aged between six to 12 years, all boys, were killed by a toy bomb and two others wounded critically," a local government official told AFP on condition of anonymity.

Another local security official confirmed the incident and casualties.

The origin of the bomb was unclear.

Dozens of children, mostly in north-west Pakistan, have lost their lives in the past when playing with "toys" that turned out to be explosive devices.

South Waziristan is also one of the seven tribal areas, where the army has for more than a decade been battling militants linked to the Taliban and Al-Qaeda.

Pakistan army launched an operation in June 2014 in neighbouring North Waziristan to wipe out terrorist bases in the tribal areas and end an insurgency that has cost thousands of civilian lives since 2004.

As a result, security has improved.