John McCain has formed a task force to prevent a repeat of the brutal smears which he believes cost him the South Carolina primary in 2000 and ultimately derailed his presidential bid.

The Arizona senator is determined to foil any negative campaigning with a group of hardened Southern political campaigners christened the “Truth Squad”. They have already been busy contesting allegations about the candidate’s marital life, military record and views on abortion.

Henry McMaster, the South Carolina Attorney-General and a member of the Squad, told The Times: “We saw the same kind of cowardly attacks eight years ago and they were an embarrassment to our state. We’re here to defend the Senator whenever things get nasty.”

In 2000, rumours and whisper campaigns accused him of treason and fathering an illegitimate child with a black woman. He lost the vital South Carolina primary election to Mr Bush that year - the winner in the state has gone on to become the Republican presidential nominee in every contest since 1980.

Mr McCain said ahead of this year’s poll: “I’m not sure the people of South Carolina would stand for it again.” But the Truth Squad has already swung into action twice in the past 24 hours.

Members have been wheeled out to defend a candidate whose strength is based on his national security credentials and a reputation as a Vietnam war hero. One of the team, a fellow former PoW called Orson Swindle, condemned a “despicable” leaflet distributed to 100 local journalists from a group called “Vietnam Veterans Against John McCain” which alleges that he collaborated with the communist enemy 40 years ago.

The pamphlet, sent to local newspaper editors, claimed he had exchanged information on fellow prisoners of war in order to secure better medical treatment for himself. Jerry Kiley, the organiser of the attack group, claimed that he is also a Vietnam veteran and said: “John McCain has created this myth that he is a hero and he is not.”

The attack echoes the infamous Swift Boat Veterans campaign which helped destroy John Kerry’s campaign to be elected President in 2004.

As well as smears on Mr McCain’s service record, his supporters have reported personal and ethical attacks.

Volunteers making campaign telephone calls for the senator have encountered a persistent rumour about Mr McCain’s divorce from his wife Carol in 1980. Another group calling itself Common Sense Issues, which supports Mike Huckabee, has been making automated telephone calls to South Carolina residents claiming that Mr McCain “has voted to use unborn babies in medical research.”

Mr Huckabee denies any connection to the group.

Mr McCain has already moved to forestall a repeat of the 2000 smear campaign involving his daughter Bridget. Leaflets landed on doorsteps across South Carolina this week explaining that she had been adopted from Bangladesh in 1993, and was not, as had been claimed, illegitimate.

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