The Afghan president was "so consistent with his complaints about night raids, civilian casualties and detentions that there was no senior Western diplomat or military leader who would have missed the fact that this was a major irritant for him," said Gen Douglas Lute, a former US ambassador to Nato.
Gen Lute said it would have been "extraordinarily unusual if there were a claim against British forces that the British chain of command was not aware of".
A spokesperson for Lord Cameron told Panorama that "to the best of Lord Cameron's recollection" the issues raised by President Karzai were about Nato forces in general and that "specific incidents with respect to UK Special Forces were not raised".
The spokesperson also said that it was "right that we await the official findings of the Inquiry", adding that "any suggestion that Lord Cameron colluded in covering up allegations of serious criminal wrongdoing is total nonsense."
Unlike many other countries, including the US and France, the UK has no parliamentary oversight of its elite special forces regiments. Strategic responsibility for their actions falls ultimately to the prime minister, along with the defence secretary and head of special forces.
Bruce Houlder KC – a former director of service prosecutions, responsible for bringing charges and prosecuting those serving in the Armed Forces – told Panorama that he hoped the public inquiry would examine the extent of Lord Cameron's knowledge of alleged civilian casualties on British special forces operations.
"You need to know how far the rot went up," Mr Houlder said.
