America has stepped up the covert targeted killing policy in Pakistan and Afghanistan despite the concern of security experts about its effectiveness and complaints by human rights groups about civilian casualties.

The CIA is said to have carried out at least 16 Predator strikes in Pakistan during the first four months of this year, compared with 36 strikes in the whole of 2008. These have killed about 161 people since President Obama’s inauguration, according to news reports in Pakistan.

David Kilcullen, who was the chief counter-terrorism adviser to Condoleezza Rice, the former Secretary of State, has said that the programme should be scrapped. “Since 2006 we’ve killed 14 senior al-Qaeda leaders using drone strikes; in the same time period we’ve killed 700 Pakistani civilians in the same area. The drone strikes are highly unpopular.” he said. “The current path that we are on is leading us to the loss of Pakistani Government control over its own population.”

Leon Panetta, the CIA director, said: “Serious pressures have been brought to bear on al-Qaeda’s leaders in Pakistan’s tribal areas. There is ample evidence that our strategy is in fact working. We do not expect to let up on that strategy.” Asked about Mr Kilcullen’s comments, he suggested that sometimes civilian deaths from other operations including less precise F-16 jet strikes are blamed on the drones.

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