Pakistani and United States troops exchanged heavy fire for the second time this week in a tribal area on the Pak-Afghan border.

The exchange took place even as President Pervez Musharraf held telephonic talks with his American counterpart George W Bush to defuse the tension from last weekend's skirmish.

According to local daily The News, Pakistani and US-Afghan forces, on the Pak-Afghan border near Angoor Adda of South Waziristan Agency, exchanged heavy machine gun fire.

There were no details of any loss to human lives or property.

Local government officials said a shell, fired from rocket launcher across the border, fell into Pakistani territory on Firday, provoking the exchange which continued for over an hour.

Pakistani officials said fresh contingents of scouts and armed forces have been dispatched to Angoor Adda to control the situation.

Last weekend tension between Pakistan and US force had mounted after an American soldier was wounded in firing by Pakistani scouts. It was further aggravated when a US plane reportedly bombed an Islamic religious school on the Pakistani side of the border.

Musharraf had a telephonic conversation with Secretary of State Colin Powell regarding last Sunday's border clash. He said there should not be a repetition of aerial bombing by US planes.

Powell assured him that utmost care would be taken in this regard by the allied forces in future, daily The Nation said.

US Central Command Chief Tommy Franks is expected to hold a teleconference either with Musharraf or Chairman of Pakistan's Joint Chiefs of Staff Committee General Aziz to discuss steps to reduce tensions.

Meanwhile, US military spokeswoman at Bagram in Afghanistan Captain Alayne Cramer and a Pakistani colonel reportedly had a verbal show down after the exchange on Friday.

Captain Cramer delivered a terse message to the colonel saying that 'enough was enough' and the US would not tolerate any firing from Pakistani side.

Captain Cramer also mentioned that the message was from 'the very top'. Franks himself wanted it to be conveyed to General Aziz, the Dawn said.

Pakistan officials refuted the US warnings by saying that "Pakistan is not Afghanistan," and it will respond appropriately to stop violation of its territory or airspace by US forces through operations not cleared by the Pakistani authorities, the Dawn quoting a senior Pakistani official said.