The U.S. military has halted the training of Afghan government-backed militias for at least a month to give the Americans time to redo the vetting of new recruits after a string of attacks by Afghan soldiers and police on their international allies, officials said Sunday.

There have been 34 insider attacks this year - at least 12 in August alone - that have killed 45 international troops, putting intense strain on the relationship between coalition forces and the Afghans they live and work with.

The shootings also have thrown doubts on one of the pillars of the U.S.-led coalition's planned withdrawal by the end of 2014 - training Afghan forces so they can take the lead for security in the country.

Lt. Col. John Harrell, a spokesman for U.S. special operations forces in Afghanistan, said the pause in training affects about 1,000 trainees of the Afghan Local Police, a militia backed by the government in Kabul.

"The training of the ALP recruits has been paused while we go through this re-vetting process, to take a look at this process to see if there's anything that we can improve," Harrell said. "It may take a month, it may take two months, we don't know."

International forces have been re-vetting Afghan forces across the board, but U.S. special operations forces decided to stop training the ones they were responsible for - the 16,000-strong ALP - while redoing the background checks.

Afghan Local Police forces that have already been trained will continue to operate, and the government will continue to recruit new members, Harrell said.

Col. Tom Collins, a spokesman for the international military coalition in Afghanistan, also said there was no set date for the training of the local police to resume.

The pause in training for the government-backed militias was first reported by the Washington Post.

Harrell said the Americans last month also put a two-week pause on operations by the Afghan special forces last month to re-vet those soldiers for any potential ties to insurgents. He did not say whether any suspicious links were uncovered.

The international forces in Afghanistan have been revisiting both security for their forces and re-examining the backgrounds of the Afghan forces in the wake of the recent attacks on international troops.

The Post also reported that training of special operations forces had been halted, but a spokesman for the NATO training mission in Afghanistan, or NTM-A, which oversees this training said there has been no such pause.

"There has been no halt in training with NTM-A assets as they relate to special forces," said Maj. Steve Neta of the Canadian military. He also said no other training programs involving the traditional military or police have been halted for re-vetting.

The head of the Afghan special operations forces said there has been no pause to the training of his forces. The program to train Afghan special operations forces had already been on break for the Muslim holy month of Ramadan and had been scheduled to restart in mid-September.

"It will continue. It is not ended at all. After the 15th of September we restart," Brig. Gen. Sayed Karim said.

The United States and its allies have been training the Afghan army and police so that they can gradually take over security for the country by the end 2014. They hope to have about 350,000 Afghans trained and ready by the end of the year, and gradually have been putting them in the lead for security in parts of Afghanistan since last year. The U.S.-run ALP project is much smaller and currently has about 16,000 members around the country.

The most recent insider attack took place last week when an Afghan army soldier turned his gun on Australian soldiers, killing three of them and wounding two more in Uruzgan province, according to the Australian military.

Afghan President Hamid Karzai's office condemned an operation by international troops to catch the shooter, describing it as unilateral and saying it resulted in the deaths of a 70-year-old man his 30-year-old son.

Karzai's office said in a statement late Saturday that the operation took place without the coordination or approval of provincial authorities and violated an agreement that calls on Afghan troops to lead night raids.

The U.S.-led international coalition responded by saying that Afghan officials approved and supported the strike.

In a related incident, NATO said it arrested a Taliban insurgent who was responsible for the May 12 shooting of two members of the British military in Lashkar Gah, the capital of Helmand province in the south.

At the time the man was a member of the Afghan police. An accomplice was shot and killed at the scene. The man, who was not further identified, was arrested along with another suspected insurgent on Aug. 30 in the Hisarak district of eastern Nangarhar province.

Prior to the two most recent attacks, coalition authorities said they believed that 25 per cent of this year's attacks had confirmed or suspected links to the Taliban, which sometimes has infiltrated the ranks of the Afghan army and police and in other cases is believed to have coerced or otherwise persuaded legitimate members of the Afghan forces to turn on their coalition partners.

Also Sunday, seven people were killed in an apparent clash between rival tribal leaders in eastern Kunduz province. The violence broke out when gunmen from one village killed the brother-in-law of a tribal leader in another, said Sarwar Husseini, spokesman for the provincial police chief.