Nato helicopter reported to have fired on border post killing three Pakistani soldiers

Pakistan blocked the main Nato supply route into Afghanistan this morning after reports that a Nato helicopter killed three of its soldiers in the second cross-border intrusion in five days.

Border officials said they had orders to block dozens of Nato trucks at the Torkham checkpost on the Khyber pass, hours after the alleged attack in Kurram tribal agency.

According to reports, the Nato aircraft opened fire on a Frontier Corps border post, killing three paramilitary soldiers and wounding at least two others. The corps is charged with guarding the notoriously ill-defined mountain border.

In Kabul a Nato spokesman said it was determining whether the incident was linked to anti-Taliban operations on the Afghan side of the border.

A Pakistan foreign ministry spokesman, Abdul Basit, said Islamabad was also inquiring into the incident. “We will complete our investigation and then formulate our response,” he said.

An official with the powerful Inter-Services Intelligence agency took a harder line, saying such aggressive incursions were a “red line” for the military. “We have for a long time given tacit approval for drone strikes. But this is an escalation we will not tolerate,” he said.

The strike comes at a sensitive time in the uneasy alliance between Pakistan and the US. At the weekend Nato helicopters chasing alleged Taliban militants fleeing into Pakistan killed between 30 and 50 people. Afterwards Pakistani military officials said they “could not guarantee security” for Nato supply convoys if such an attack were to reoccur.

US military figures show that supplies pass though Pakistan at a rate of 580 truckloads per day. The Associated Press, citing government officials, said about 100 trucks had been stopped this morning.

Yesterday the CIA chief, Leon Panetta, arrived in Islamabad for meetings with the ISI chief, Lieutenant General Shuja Pasha. The US is redoubling its pressure on Pakistan to mount fresh anti-Taliban operations in the tribal belt stronghold of North Waziristan.

The CIA has carried out 21 drone strikes so far this month, mostly in North Waziristan – the most intense barrage since the strikes began six years ago.

The surge may be linked to the discovery of an alleged al-Qaida plot involving Mumbai-style attacks on cities in the UK, Britain and France, which is said to have originated in Pakistan’s tribal belt.

British and German officials said the plot had reached the planning phase but was not sufficiently advanced to justify raising the national threat level. The Eiffel Tower was temporarily closed this week after officials received an attack threat. It was not clear whether it was related to the Pakistani plot.

American and Pakistani officials co-operate closely on the drone strikes – Pakistani generals say they have witnessed live video feeds of the attacks – but are at odds over how to deal with the Taliban safe havens in the tribal belt.

This summer the Wikileaks “war logs” disclosed details of numerous fraught exchanges, some violent, between Pakistani, Afghan and Nato troops along the mountainous frontier.

Last December the then commander of US troops in Afghanistan, General Stanley McChrystal, said his troops would not enter Pakistan to attack militants. “My authorities stop at the border,” he said.

But there are also reports of a secret agreement between Pakistan and the US that allows “hot pursuit” across the lawless border up to 10 kilometres into Pakistani territory.

In June 2008 US gunships attacked a Pakistani border post in Mohmand tribal agency, killing 11 soldiers. It caused an outcry in Pakistan, but the furore subsided and later that summer the drone campaign started in earnest.

One of the latest strikes is reported to have killed the al Qaida “number three”, Sheikh Fateh al-Misri. The militant who previously held that position, Mustafa Abu al-Yazid, was killed in an earlier drone strike last May.

Panetta is reported to be urging Pakistani generals to concentrate their forces on the Haqqani network based in North Waziristan in the tribal belt.

One American official told the Guardian that the group’s commander, Sirajuddin Haqqani, may have become as powerful as the Taliban leadership council known as the Quetta shura.

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