WASHINGTON, Aug 26: US officials have refused to endorse Afghanistan’s claim that Pakistani spies have infiltrated their security forces and were attacking American and Nato troops, dressed as Afghan soldiers.

“It's our understanding that these attacks aren't the work of foreign intelligence services,” a senior US defence official told Wall Street Journal. Citing US investigations of the incidents, the official said: “They're typically Afghans who themselves decide to conduct them, and some Afghans from insurgent networks might have helped on occasion.”

Afghan President Hamid Karzai issued a statement earlier this week, insisting that “foreign spy agencies” had infiltrated Afghan security forces and were now using their uniforms to attack US and Nato troops.

They were responsible for taking the lives of 40 coalition members this year, he said.

Although President Karzai did not name the agency, other Afghan officials told Western journalists he was referring to Pakistan’s ISI which, they said, was responsible for these attacks. Later, an Afghan presidential spokesman, Aimal Faizi, said that they had conducted an investigation into the attacks and concluded that “foreign spy agencies are growlingly fearful of the empowerment of Afghan security agencies” and that’s why they were masterminding those attacks.

“The countries behind the attacks are from the region,” he claimed.

But America’s top military commander in Afghanistan, Gen John Allen, asked Kabul to provide evidence to support the claim.

“I'm looking forward to Afghanistan providing us with the intelligence that permits them to come to that conclusion so that we can understand how they've drawn that conclusion and we could add that into our analysis,” he told reporters in Washington.

“But we'll wait to make a definitive statement on that issue until we've seen their intelligence in that regard,” said the US general, speaking via satellite link from Kabul.

Various US media outlets carried detailed reports on this issue, pointing out that the US-led coalition in Afghanistan believed only about one of every 10 insider attacks is committed by Taliban infiltrators.

“Overwhelmingly, the so-called green-on-blue attacks are perpetrated by Afghan security members who are culturally offended by or have personal disputes with their international counterparts,” said a report quoting US official sources. The L.A. Times described this as “a potentially serious rift” between the Afghan and US governments, noting that US and Nato officials “have consistently said most of the shootings … stem from personal disputes, stress, cultural differences and battle fatigue”.

This week, the chairman of the US Joint Chiefs of Staff, Gen Martin Dempsey, visited Kabul for talks on the issue and President Karzai’s statement blaming “foreign spy agencies” came a day after his meeting with Gen Dempsey.

“US and other Western military officials have never singled out the ISI as the main culprit in insider attacks,” the newspaper noted.

Insider attacks were symptomatic of deeper challenges the US and its allies face in their effort to withdraw almost all allied combat forces and turn over security to the Afghans by the end of 2014, said the report.

“The hostility (towards foreign troops) is rooted in frustration over perceived American support for what many Afghans consider an ineffective and corrupt Karzai government, raids that have killed innocent civilians, and US military convoys and bases that are frequent reminders of foreign presence on Afghan soil,” noted the Bloomberg news agency.

The New York Times underlined “another sign of vulnerability” for the mission to train Afghan security forces: “even greater numbers of the Afghan police and military forces have killed each other this year.”

So far, Afghan soldiers or police officers have killed 53 of their comrades and wounded at least 22 others in 35 separate attacks this year, according to Nato data provided to The New York Times by officials in Kabul.

By comparison, at least 40 Nato service members were reported killed by Afghan security forces or others working with them.

The newspaper noted that US and Nato officials were also concerned about cultural clashes within the rapidly expanding Afghan forces themselves, “raising questions about their ability to weather the country’s deep factional differences after the Nato troop withdrawal in 2014”.