The top United States commander in Afghanistan, General David Petraeus, has ordered a probe into allegations that members of a psychological-operations team - known as psy-ops - were ordered to target US senators and other visiting dignitaries to help to persuade them to provide new troops and money.

Among politicians reportedly targeted by the team, whose ostensible mission is to manipulate the thought processes of the enemy, were former presidential candidate John McCain and fellow senators Al Franken, Carl Levin, Joe Lieberman and Jack Reed.

The man in charge of psy-ops, Lieutenant-Colonel Michael Holmes, told Rolling Stone magazine he received orders to turn his focus on visiting politicians from Lieutenant-General William Caldwell, one of the top commanders in the country. "How do we get these guys to give us more people? What do I have to plant inside their heads?" the chief of staff to Caldwell purportedly asked Holmes.

That Petraeus reacted so quickly reflects the potential gravity of the claim. Using psy-ops on your own side is prohibited by Pentagon policy and likely to be seen against US law.

The article was penned by Michael Hastings, who last year wrote an article about a climate of disrespect among commanders towards President Barack Obama. That piece resulted in the firing of the then US Commander, General Stanley McChrystal.

Holmes told the magazine he resisted the order but was reprimanded for it. Among the allegations was a claim that his men were told to compile profiles of the politicians to identify things such as their voting records on the war, their likes and dislikes and the things that aroused their passions.

"My job in psy-ops is to play with people's heads, to get the enemy to behave the way we want them to behave," Holmes was quoted as saying by Rolling Stone. "I'm prohibited from doing that to our own people. When you ask me to try to use these skills on senators and congressmen, you're crossing a line."

Reed said he found the claims "serious and disturbing".

A spokesman for Caldwell gave a statement which said he "denies the assertion that the command used an Information Operations Cell to influence distinguished visitors".