Al Jazeera's tribal affairs specialist Kamal Hyder in Peshawar, bordering the tribal area in north-west Pakistan, said trouble has been brewing in the region since local leaders signed a peace deal with the Pakistani government.
He said: "They [locals] were under pressure to ask the al-Qaeda linked militants to lay down their weapons in return for a blanket amnesty. And Pakistan's government itself is coming under increasing pressure to dislodge these people from that area."
"Dick Cheney, when he came to Pakistan, told the Pakistanis that they should do more and try to get these militants to leave this area immediately. The Americans were also threatening they would bomb these areas if necessary - they had done that in the past."
Militants in north and south Waziristan have killed dozens of people, including government officials, tribal elders they accused of supporting the Pakistani government and people accused of spying for US forces in neighbouring Afghanistan.
While many people have been assassinated by the militants, the fighting on Tuesday was the first reported clash between the militants and ethnic Pashtun tribesmen in the area.
Hyder said: "This clash may jeopardize safe sanctuaries for these militants because they have heavily depended on local hospitality and local people may find that their guests have outlived their welcome."
The fighting on Tuesday broke out in the village market after militants tried to assassinate a pro-government tribal elder, Malik Saeedullah Khan, intelligence sources said. A brother of Khan was killed, one official said.
|"This clash may jeopardize safe sanctuaries for these militants because they have heavily depended on local hospitality and local people may find that their guests have outlived their welcome"|
Kamal Hyder, Al Jazeera's correspondent in Peshawar, Pakistan
The militants opened fire at Khan, the head of a government-backed peace committee, as he passed through the market area.
Khan escaped unhurt and later up to 250 tribesmen went to the bazaar and exchanged fire with the militants.
Another intelligence official, referring to the main town in south Waziristan, said: "Sporadic fighting is still going on and angry tribesmen have blocked the road linking Azam Warsak to Wana."
It was the second time the Uzbeks had tried to kill Khan in three days.
An intelligence official said the Uzbek fighters belonged to the Islamic Movement of Uzbekistan (IMU) militant group.
Azam Warsak and nearby areas were the scene of fierce fighting in 2004, when Pakistani security forces launched a major operation against militants commanded by IMU leader, Tahir Yuldashev.
More than 100 people were killed in that fighting but Yuldashev, who is accused of a series of bomb blasts in the Uzbek capital, Tashkent, in 1999, escaped.