KABUL: The Haqqani insurgent network, allegedly based in Pakistan and with ties to Al Qaeda, is suspected of being a driving force behind a significant number of the ''insider'' attacks by Afghan forces that have killed or wounded more than 130 US and allied troops this year, American officials say.  

Until now, officials had said the attacks seemed to stem either from personal grievances against the allies or from Taliban infiltration. The Taliban have publicly claimed to be orchestrating the campaign to subvert the so-called US-Afghan alliance.

New data provided to The Associated Press this week also reveal that in addition to 35 US and allied troops killed in insider attacks last year, 61 were wounded.

Those included 19 in a single attack in the eastern province of Laghman on April 16, 2011, in which six American servicemen were killed. Thus far in 2012 there have been 53 killed and at least 80 wounded, the figures showed.

Haqqani involvement in the plotting would add a new dimension to that group's insurgent activity, which has been marked largely by spectacular attacks against targets inside Kabul.

Haqqani leaders have pledged allegiance to Taliban leader Mullah Omar, but the group largely operates independently. The two groups have a shared interest in evicting foreign forces.

The US officials said Friday that although there was no hard evidence tying the Haqqanis to specific attacks, the pattern of shootings and the movements and backgrounds of some of the shooters, including travel into Pakistan shortly before the shootings, pointed to a likely connection to the group that Washington last month officially labelled a terrorist organisation.

The officials spoke on condition of anonymity in order to discuss inferences drawn from internal US military analyses of a string of murderous attacks over the past two years that have angered the allies, embarrassed the Afghan government and threatened to undermine the war in Afghanistan. The officials were not authorised to make the comments publicly.

The US-led military coalition recently slowed its partnering with some Afghan forces on a temporary basis, partly in response to a recent spike in insider killings.

The data on the attacks provided to the AP reveal that shootings in 2012 have been concentrated more in the Pashtun south and the swath of Pashtun territory that forms the southern approaches to Kabul.

In 2011 the attack pattern was more dispersed, although the largest number occurred in the south and the east.

The internal military analyses, based in part on that data, indicate that a number of shooters were recruited into the Afghan army or police forces from Pashtun areas in eastern Afghanistan, including the provinces of Paktika, Paktia and Khost where the Haqqanis wield great influence, the officials said.

In some cases these Afghans, most of whom had served in uniform for six months or less, returned to those areas on leave from their army or police duties, or briefly crossed into Pakistan, shortly before turning their guns on American or allied soldiers, the officials said.

Officials say the Afghan government is now watching such movements more closely and taking other steps to prevent additional insider attacks, although the US believes they will not end.

Of the 38 reported attacks so far this year, 10 happened in Kandahar province, the spiritual and traditional home of the Taliban, and 10 happened in neighboring Helmand province, also a heavily Pashtun area.

Ten others were in or near a Haqqani-influenced swath of territory along the southern approaches to Kabul, including the latest attack on Sept 29 in which Army Sgt. 1st Class Daniel T. Metcalfe, 29, of Liverpool, NY, and a US civilian were killed by Afghan soldiers. They were killed in the same district of Wardak province, southwest of Kabul, where a July 3 attack by a rogue Afghan soldier wounded five American soldiers.

''The truth of it is, the removal of this threat completely would be extremely difficult because of the varying nature of the motivations'' of the attackers, said Australian Brig. Gen. Roger Noble, a senior operations officer on the staff of the Kabul-based international coalition.

Noble said that while he knew of no Haqqani ties to the attacks, the killings were a means of dividing the Afghans from their ‘allies’ that is ''right up their alley.''

Jeffrey Dressler, an analyst at the Washington-based Institute for the Study of War, who has extensively studied the Haqqani network, said Friday that US suspicions may be well-founded.

''If we accept the notion that a proportion of the 'insider attacks' are due to infiltration, then it is absolutely plausible to assume that the Haqqanis are responsible for a portion of those,'' Dressler said in an email exchange. ''The tactic of 'insider attacks' is certainly a potent one, so I would also suspect that the insurgency is doing all it can to increase the frequency and lethality of the incidents.''

The Haqqani network is regarded as one of Afghanistan's most experienced and sophisticated insurgent organisations.

The network allegedly maintains a safe haven in North Waziristan, Pakistan, across Afghanistan's southeastern border. The Pakistani army has consistently refused to launch a military operation in North Waziristan despite the allegations that senior Al Qaeda leaders are present in the tribal region.

Australian Maj. Gen. Stephen Day, the plans chief for the international coalition's joint command, said in an interview that the Haqqanis were a more troublesome military challenge than the Taliban.

"They represent the most dangerous threat because they are the best trained, best resourced opponent we have," Day said on Thursday. He was not speaking about the question of a Haqqani link to insider attacks.

When the number and lethality of insider attacks began to accelerate early this year, US and coalition officials were reluctant to release details, including those cases in which the shooter missed or wounded but did not kill his target. The attacks were dismissed as isolated incidents. That changed over the summer as top US, Afghan and Nato officials began speaking about them more and publicly pressing for solutions.

On Friday, the AP was given a previously unreleased set of data about 2012 and 2011 insider attacks.

The data show that in addition to the 53 US and allied personnel killed so far this year, more than 80 have been wounded. Although the coalition had previously said there were 21 attacks killing 35 allied personnel in 2011, it had not said that another 61 were wounded.

The statistics also show a previously unreported pattern of attacks happening either in multiple locations on the same day or on consecutive days. This has been the case 10 times so far this year, and Noble said he and other officials were unable to explain the significance of this.