WASHINGTON, July 16: The US defence secretary and a top military official on Wednesday dismissed the reports as “untrue” that American troops were massing on the Afghan border to launch an attack into Pakistan but warned that if attacked the troops will return the fire.

Defence Secretary Robert Gates also dismissed the suggestion that the current tension between Pakistan and Afghanistan could lead to a war between America’s two key allies. “That is an exaggeration,” said Mr Gates when asked if the current situation could lead to a Pakistan-Afghan war.

At the Pentagon briefing, both Mr Gates and Admiral Mullen were asked to comment on recent media reports that the US was gathering troops on the Afghan border to launch an attack into Pakistan’s tribal areas.

“The notion that US troops are massing on the border to enter Pakistan is untrue,” Mr Gates told a Pentagon news conference.

Admiral Michael Mullen, chairman of the US Joint Chiefs of Staff, also dismissed these reports as incorrect. “I have seen the reports and disagree with them, disagree with what they say,” Admiral Mullen told the briefing.

Mr Gates clarified that the US has not taken any decision to send troops into Pakistan’s tribal areas in search of Al Qaeda or Taliban leaders but if the troops were attacked from across the border, they will return the fire as they have done in the past, using long-range artillery.

Admiral Mullen said that during a recent visit to Pakistan he told Pakistani leaders they need to do more to stop cross-border infiltrations into Afghanistan.

The Pentagon said earlier that the admiral made an unscheduled visit to Islamabad last week to share US concerns over Pakistan’s inability to stop cross-border attacks.

“The reality is that Pakistan faces security challenges of its own from these groups,” said Mr Gates when asked what leverage the US has to persuade Pakistan to stop cross-border attacks. “The number of attacks inside Pakistan has doubled.”

The new civilian government in Pakistan, he said, needs to gain a full appreciation of “the significance and magnitude” of the threat from the terrorist groups to be able to deal with it. “The first thing is a clear understanding and we can make a contribution there, we are ready and willing to help them.”

Admiral Mullen said that he sees this threat expanding and “becoming a syndicate of terrorist groups. The Pakistani leaders he met during his trip, acknowledged the threat. “(Now) they need to really figure out a way with the Afghans and with our security forces” to fight this threat, he said.

Secretary Gates noted that Pakistan has conducted some military operations in the tribal areas in the last couple of weeks. “So they have identified the problem and taken military action. Our hope obviously is that those efforts will intensify.”

Asked to comment on White House hopeful Barack Obama’s statement that he will send US troops into Pakistan to catch Osama bin Laden, Admiral Mullen said: “We will all like to catch Bin Laden.”

He said that while US and Afghan troops can fight back the militants, “the pressure on the Pakistani side is needed.”

Secretary Gates said while sending more US troops to Afghanistan will make a significant difference to the situation, “there’s no question that the absence of pressure on the Pakistani side is creating opportunities for the insurgents to launch attacks.”

The situation will be much better if there were pressure on the Pakistani side, agreed Admiral Mullen.