The US State Department has rebuked a private security firm over the "aggressive behaviour" of guards hired to protect Afghan leader Hamid Karzai.
US private security contractors are never far from Mr Karzai's side
US State Department's Richard Boucher said the issue was raised with DynCorp, the company that supplied the guards.
There have been several reported cases of apparently over-zealous and insensitive conduct on the part of Mr Karzai's private security contractors.
A BBC correspondent recently saw one of the guards slap an Afghan minister.
Crispin Thorold reported seeing the Afghan transport minister receive a slap from one of Mr Karzai's security guards on a visit to the northern city of Mazar-e-Sharif.
An article in the New York Times argued that the bodyguards were feared and resented by many who came into contact with them in Afghanistan - including visiting European diplomats.
Mr Boucher said the complaints of aggression had been taken up with DynCorp managers as well as its staff in Afghanistan.
He also praised the company for having successfully kept Mr Karzai out of danger.
A spokesman for DynCorp's parent company told the Associated Press news agency it was working closely with the State Department to do the "best possible job" in a "difficult, dangerous and challenging environment".
At least three US citizens died when a bomb was detonated outside DynCorp offices in Kabul in August.
Mr Karzai is thought to be a prime assassination target for militants linked to the former Taleban administration who continue to oppose the US presence in Afghanistan.
Rockets were fired at a helicopter carrying him on a rare visit outside Kabul in the run-up to last weekend's presidential elections.