American forces who are blamed for killing up to 92 civilians in a bungled operation in Western Afghanistan were misled by misinformation from a tribal rival of those who died, according to Spain's intelligence service and Afghan government sources.

Spanish intelligence sources said that the joint operation between US special forces and Afghan commandos had been planned on the basis of a false intelligence tip from a tribal leader who said that senior Taleban figures were due to meet in the village of Nawabad on the night of August 21. Spain has just under 1,000 troops based in the province of Herat, where the incident occurred.

Investigators and local Afghan politicians also suggested that a private grudge was behind false intelligence fed to the US force.

The rival clans were competing for lucrative security company contracts for the US airbase at Shindand and for control of drug-smuggling routes into nearby Iran, according to sources close to one of three investigations into the attack.

Aziz Ahmad Nadim, a local MP who took part in the Afghan government investigation into the attack, told The Times that there were tensions between two leaders within the Noorzai tribe: Reza Khan and Nader Tawakal.

Most of the victims of the attack were from the extended family of Reza Khan, whose brother was killed as part of the same longstanding feud six months ago. His family compound was levelled by US aircraft.

Mr Nadim said that the ceremony attacked was a six-month anniversary memorial for the dead chief, for which about 1,000 invitations had been sent to members of the tribe. Sources close to the UN inquiry into the attack told The Times that investigators were shown printed invitation cards to the commemoration.

“Most of the guys killed were working with the US forces at Shindand,” said Mr Nadim. “I asked the US commander why they did it. Why not surround the village and find out who is there? He had no answer.”

A US investigation found that only seven civilians died in the attack, but on Sunday the Pentagon announced that it was reopening the inquiry after the emergence of new evidence, including videos of the carnage.

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