Islamabad: Pakistan Army chief Gen Ashfaq Parvez Kayani has not ruled out the possibility of a unilateral US military strike against militants in North Waziristan tribal region, but warned that Washington will have to think "ten times" before launching such an attack, a media report said on Wednesday.

"They (US) might do it but they will have to think ten times because Pakistan is not Iraq or Afghanistan," Kayani was quoted by a newspaper as telling members of the Parliament's defence committee during a briefing at the General Headquarters on Tuesday.

The rare briefing for members of the standing committees on defence of the two houses of the Parliament lasted over three hours, media reports said.

Kayani made the remarks when a lawmaker asked him to comment on the possibility of a US strike in Pakistan, like American attacks in Laos and Cambodia before the withdrawal from Vietnam.

The US has been putting up pressure on Pakistan for years to go after Haqqani network militants in North Waziristan, who cross the border to attack US and NATO forces in Afghanistan.

The pressure has become intense since US Navy SEALs killed Osama bin Laden in May in Abbottabad.

However, another newspaper quoted Kayani as ruling out the possibility of an "immediate unilateral US military offensive in North Waziristan".

Kayani acknowledged that the US was pressing Pakistan to launch a military operation in North Waziristan and said an ongoing build-up of Afghan and International Security Assistance Force troops along the Pakistan-Afghanistan border is a tactic to "intensify that pressure", a report stated.

"We have made it clear to the US that we will decide the timing of any such action according to our situation and capabilities. We have also told them that the problem lies within Afghanistan. If anyone convinces me that everything will be sorted out if we act in North Waziristan, I will take immediate action," Kayani was quoted as saying.

Kayani said Pakistan had provided its position on Afghanistan in writing to the US administration in 2010 and asked the Americans to elaborate their position but they had not done so.

Kayani said some principles govern relations between countries and "nobody would be allowed to cross the red line".

He rejected a perception that Pakistan wants to control Afghanistan and said this was evident from history that nobody ever succeeded in doing so.

Pakistan will never allow its territory to be used for attacks against any other country, he said.

Kayani further said the US had been told that Pakistan did not need military aid, adding he had received a call from Washington asking if he meant it.

"My reply was we mean what we say," he said.

He said only 20 per cent of the USD 1.5 billion of aid under the Kerry-Lugar Act had so far been received.

Asked about allegations that the Inter-Services Intelligence had "unsavoury characters", Kayani said intelligence came from links and all international intelligence agencies, including CIA and MI6, have such contacts. He stressed these contacts must be positively used.

He said the law of evidence is outdated and not in conformity with the current scenario.

A bill seeking to amend the Anti-Terrorism Act of 1997 has been pending before a parliamentary committee for almost a year, he noted.

This was probably the first time that two parliamentary panels attended a briefing on national security at the General Headquarters.

Maj Gen Nadeem informed the lawmakers that Taliban activity in Afghanistan had increased 40 per cent despite 10 years of foreign military presence.

Tension mounts on Af-Pak border

Meanwhile, Pakistan has deployed additional army and paramilitary troops along its border with Afghanistan in the wake of a new push by Afghan and NATO forces against the Haqqani network that is based in the restive North Waziristan tribal region.

Regular army and Frontier Corps troops have been sent to areas along the border with Afghanistan to stop militant attacks, chief military spokesman Maj Gen Athar Abbas said.

Pakistan will not allow militants to carry out attacks on its check posts and border villages and kill civilians, he added.

Abbas said the additional forces were sent after NATO and Afghan forces failed to act on Pakistan's call for action against militants responsible for cross-border attacks.

About 100 Pakistani security personnel have died in cross-border attacks by Afghanistan-based militants during the past four months, Abbas told a radio channel.

The International Security Assistance Force was informed about these attacks and the location of militant hideouts in Afghanistan was pointed out but no action had been taken so far, he said.

Apparently there is no presence of the Afghan army or ISAF forces in the "vast area" from where militants were operating against Pakistan, he said.

The Dir region in Khyber-Pakhtunkhwa province was hit hardest by the cross-border attacks and terrorists who fled the Swat valley to escape a Pakistani military offensive were involved in these attacks, Abbas said.

The militants were launching these attacks from Afghan territory so that they could return to Swat via Dir, Abbas contended, adding all check posts along the Afghan border have been strengthened and the number of posts in Dir increased.

Abbas claimed the militants had safe havens in the Kunar, Nuristan and Ningarhar provinces of Afghanistan, where "there are no security forces".

Afghan Defence Minister Abdul Rahim Wardak said in Kabul that "Operation Knife Edge" had been launched to "deliver a crashing blow to enemy's capabilities to conduct operations especially terrorist operations during the winter".

Afghan army chief Sher Mohammad Karimi said the operation was being conducted along the border because the "enemy lately operates along the border on both sides". Other Afghan officials said it was "largely against the Haqqani network".

NATO spokesman Capt Justin Brockhoff confirmed "enhanced official operations" were being conducted "to reduce the select insurgent network" in an eastern region that borders Pakistan.

US forces report jump in infiltration from Pakistan

As American-backed Afghan forces' massive operation 'Knife Edge' got underway in eastern Afghanistan, US and NATO forces have said that infiltration and cross-border attacks emanating from Pakistan have jumped up.

Significant increase in the Haqqani network activity in Khost, Paktia, Logar and Wardak has been reported which are on infiltration routes from Pakistan to launch attacks against the Afghan capital, a news channel reported quoting top NATO officials in Kabul.

"Whether or not NATO and US will have to provide more assistance to the Afghan forces along the border with Pakistan," the officials said would depend on "the level of threat coming out of Miranshah".

General John Allen, the commander of US and NATO forces in Afghanistan, has completed a 90-day assessment of the campaign plan and suggested a gradual shift of focus to pulverise Haqqani network militants in the east.

"As things improve in the south, we will focus more on the east," officials said.

Though US officials have given bare details about the build-up to launch the new operation against the Haqqani terror network, Pakistani media reports have said that heavy artillery, fresh troops and helicopter gunships have been moved closer to the border to hit Haqqani terror network's stronghold in the region.

The new Afghan operation in the east against the Haqqani militants comes as Pentagon said that cross-border attacks emanating from Pakistan against US-led forces in Afghanistan have increased since the US raid that killed Osama bin Laden in Pakistan.