The CIA has received authorization to target a wider range of targets in Pakistan with its drone-guided missiles, despite national discontent on growing civilian death toll.

The US will expand its drone attacks in Pakistan's tribal regions, including low-level fighters whose identities may not be known, US officials said Wednesday, quoted in a Reuters report.

The report says the targets include what has been described as 'all militants'.

The US drone strikes began to expand under former President George Bush and have further intensified under President Barack Obama.

Washington claims the strikes are vital in protecting foreign troops in the region and that the targets are selected with 'extreme care'.

The announcement comes as more than 850 people, mostly civilians, have been reported killed in nearly 100 raids by American pilotless planes since August 2008.

In 2009, the CIA launched 44 strikes in North and South Waziristan but managed to kill no more than a handful of notable militants, Anti-War.com reported on its January 14th edition.

Islamabad has repeatedly condemned the strikes, saying they threaten the country's sovereignty, with little impact, since the US raids have continued to intensify.