US drones targeting suspected militants have fired missiles killing about thirty people in Pakistan's troubled South Waziristan, leaving dozens injured.

The Wednesday strike was the second drone attack of the day in the area controlled by Pakistan militant chief Baitullah Mahsud.

The death toll is expected to rise as some of the injured are said to be in critical condition.

At least 14 people were killed during a similar attack earlier in the day which took place in the same region near the Afghan border.

Hundreds of Pakistanis have lost their lives in such attacks, which started under the Bush administration in 2006.

Officials in Islamabad have long denounced the strikes on their soil.

JR/MMN