Civilians are being "terrorised" 24 hours a day by CIA drone attacks that target mainly low-level militants in north-west Pakistan, a report by Stanford and New York Universities says.
It claims that follow-up strikes are also killing rescuers who set out to treat the injured.
The report, made up of interviews with victims, witnesses and experts, pins blame on US President Barack Obama for the recent increase in "signature strikes" which target groups selected through "pattern of life analysis" and which have resulted in large, innocent groups attending weddings and funerals being killed.
It states: "US drones hover 24 hours a day over communities in north-west Pakistan, striking homes, vehicles, and public spaces without warning.
"Their presence terrorises men, women, and children, giving rise to anxiety and psychological trauma among civilian communities. Those living under drones have to face the constant worry that a deadly strike may be fired at any moment, and the knowledge that they are powerless to protect themselves.
"These fears have affected behaviour. The US practice of striking one area multiple times, and evidence that it has killed rescuers, makes both community members and humanitarian workers afraid or unwilling to assist injured victims."
The report entitled Living Under Drones calls into question the effectiveness of drone attacks as a weapon against terrorism in Pakistan, stating that it is overplayed by the US government.
It says: "The dominant narrative about the use of drones in Pakistan is of a surgically precise and effective tool that makes the US safer by enabling 'targeted killings' of terrorists, with minimal downsides or collateral impacts. This narrative is false."
Drone attacks are thought to have killed hundreds of militants in Yemen and Afghanistan as well as Pakistan, including Senior al-Qaeda and Taliban leaders.
But the report highlights the difficulty in obtaining accurate data on casualties "because of US efforts to shield the drone programme from democratic accountability, compounded by obstacles to independent investigation of strikes in North Waziristan".
The "best available information", they say, is that between 2,562 and 3,325 people have been killed in Pakistan between June 2004 and mid-September this year – of whom between 474 and 881 were civilians, including 176 children. The figures have been assembled by the Bureau of Investigative Journalism, which estimated that a further 1,300 individuals were injured in drone strikes over that period.
Hours before the report was released, another drone strike hit the Mir Ali area of North Waziristan, killing eight fighters, most of them Uzbeks and Tajiks, a spokesman for the Pakistani Taliban told the BBC. Pakistani intelligence officials earlier said five had been killed.