Pakistan's army says it has never helped U.S. artillery troops in Afghanistan direct fire onto the Pakistani side of the border, and that no such cross-border shelling has ever taken place.

Speaking in Washington on Tuesday, a senior U.S. commander in Afghanistan, Colonel Cardon Crawford said Pakistani forces had helped U.S. artillery shell Afghan anti-government insurgents hiding on the Pakistani side.

He called the action a "huge step forward" in cooperation between the two armies.

A spokeswoman for the U.S. command in Afghanistan later said the colonel's remarks referred to a specific incident on November 6.

But the top Pakistani military spokesman, Major General Shaukat Sultan Khan, says the statement is baseless.

"It is absolutely wrong. There is no fire from the Afghanistan side into the Pakistan side like this, and coordinated by the Pakistani military. There is nothing of this kind," he insisted.

But he adds that other forms of military cooperation are taking place.

"The cooperation is definitely there, but the cooperation is in terms of the passage of information, intelligence sharing, etc.," he said.

Pakistan, however, has previously accused Afghan national forces of conducting occasional small arms fire at targets on the Pakistani side of the rough mountainous border.

Pakistan's government has been a close ally in the U.S. war on terror, and Pakistani security forces have captured of number of key members of the al Qaida terror network. However, the government's relationship with the United States is controversial and many Islamic groups oppose it.