At least 70 people are reported to have been killed and dozens injured in a major battle between Taliban fighters and another tribal group in Pakistan.

The fighting in South Waziristan erupted when fighers loyal to Baitullah Mehsud, the Pakistani Taliban chief, attacked the followers of Turkistan Bittani, who allied with the government after defecting the Taliban.

Bittani said that over 1,000 Mehsud fighters took place in the offence.

"It was a very well-organised attack and Taliban fired with heavy machine guns, rocket-propelled grenades and assault rifles," a Pakistan intelligence official, who spoke on condition of anonymity, said on Wednesday.

"According to the initial information, 70 people have died and many more are injured while Taliban also destroyed 35 houses," he added.

'Strong and confident'

Most of those who died in the fighting in the Jandola area were from Bittani's fighters.

Bittani told German Press Agency dpa that 100 fighters died in the clashes while "our 40 houses have been destroyed.

"We have pushed them (Taliban) back but exchange of fire still continues," he said.

Al Jazeera's Kamal Hyder said: “If Bittani reports are accurate, it would be indicative of the fact that the Pakistani Taliban are still quite strong enough and confident enough to launch such a big attack."

Another intelligence official said government troops had started to pound Taliban fighters with artillery fire, forcing them to retreat.

"There several vehicles have been hit and their men have also died, but we don't have exact figures," he said.

The fighting comes one week after a US missile strike in South Waziristan reportedly killed Mehsud.

The US and Pakistani officials say they are almost certain last Wednesday's strike killed the Taliban leader, but several Taliban fighters have insisted Mehsud is alive.