Washington: The first three months of this year has experienced a sharp decline in the US drone attacks inside Pakistan's tribal region which is home to Taliban and al-Qaeda militants, a report said.

In a report, Washington-based think-tank New America Foundation said that there were 11 drone strikes in the first three months of this year as against 21 in 2011 and 28 in 2010.

"There were 70 drone strikes in Pakistan's tribal regions in 2011, down from 118 in 2010, which saw the peak number of strikes since the programme began. The drop in drone strikes during 2011 was because a series of events that wore on the ever-fragile US-Pakistan relationship," it said.

According to the report, the Obama Administration last year had ordered evaluation of the drone strikes in Pakistan.

The study found that the CIA was primarily killing low-level militants in its drone strikes, it said.

"Those results prompted the government to implement new rules in November governing when and how specific drone strikes were authorized. The State Department was given a larger say in the decision-making process. Pakistani leaders were promised advanced notification of some strikes. The CIA pledged to refrain from conducting strikes during visits by Pakistani officials to the United States," the report said.

The think-tank, which maintains a data base on the drone strikes and casualties, said as the years have progressed, the drone strikes have become more precise and discriminating.

"There is still considerable debate over how the US government defines a "militant" and how easily it is able to distinguish between militants and civilians from a drone cruising tens of thousands of feet above the ground," it said.

Referring to a survey conducted by it in the tribal areas of Pakistan in the summer of 2010, the think-tank said almost 90 per cent of the respondents in the region where the drone strikes are located opposed US military operations in the region.