KABUL, Afghanistan -- Hundreds of Afghan service members have been arrested and expelled after a string of rogue shootings killed dozens of NATO personnel, the country's Ministry of Defense said Wednesday.
"Hundreds were sacked or detained after showing links with insurgents," ministry spokesman Zahir Azimi told reporters. "In some cases we had evidence against them, in others we were simply suspicious."
Those arrested were thought to have ties to criminal elements and those expelled were deemed to have irregular paperwork, mental-health problems or false documentation, Azimi told NBC News.
The move comes during the worst year for such insider, or "green-on-blue", attacks. At least 45 members of the NATO-led force have been killed by Afghans in uniform this year, including 15 in August alone. That compares with 35 killed in such attacks in all of 2011.
US 'insider' killings mount in Afghanistan
The spike of insider attacks has sparked concerns that Afghan forces will not be capable of taking over security by 2014 as planned.
Azimi told NBC News that his ministry started an investigation into the killings within the 195,000-strong Afghan army three or four months ago.
But tensions are still simmering. The shooting dead of three Australian troops by an Afghan army sergeant in the south last week prompted a deadly raid to find the rogue soldier, causing a war of words between Canberra and Kabul.
U.S. forces in Afghanistan said on Sunday they had suspended training new recruits to the Afghan Local Police, a militia separate from the national police, following the spike in insider attacks.
Seventeen villagers beheaded in southern Afghanistan after 'music party'
And on Wednesday, NATO's top official told President Hamid Karzai that he was deeply concerned about the surge in assaults by Afghan troops on their foreign allies.
Spokeswoman Carmen Romero said Karzai had assured Secretary-General Anders Fogh Rasmussen in a phone conversation that he was doing all he could to stop the attacks.
U.S. Gen. John R. Allen, who commands NATO's 129,000-strong force, briefed the alliance's top decision-making body on Wednesday about the attacks, The Associated Press reported.
Reuters and The Associated Press contributed to this report.
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