About 50 to 100 Afghan soldiers are killed in battle every week but the high casualty rate does not mean the country's forces are at the breaking point, AFP reports citing a US general.
"The Afghan security forces are suffering more casualties, no question about it," Lieutenant General Mark Milley said by video link from Afghanistan.
Milley, the deputy commander of US forces in Afghanistan, said "somewhere in the range of 50 to 100 or so Afghan security forces are killed in action per week."
"And that's not at all insignificant. That is significant. And we're paying attention to that," he said.
The general said the casualty rate approached losses suffered by American forces in the Vietnam War, a conflict that claimed the lives of about 58,000 US troops.
NATO's US-led force is working to help Afghan army and police improve their tactics, conduct medical evacuations and counter roadside bombs to "minimize" casualties, Milley said.
As Afghan forces employ more helicopters, artillery and mortars, their casualties are expected to decline, he said.
But Afghan forces were resilient and could withstand the casualties because he said they were determined to prevent Taliban militants from taking back political power, he added.
"They're hard. They're tough. And I don't think the rates of casualties, although significant, I don't think that's going to shatter or break the security force," said Milley, the head of the NATO-led force's joint command.
The top commander of NATO and US forces, General Joseph Dunford, voiced concern at casualties being suffered by Afghan forces in an interview with the Guardian published Tuesday.
"I'm not assuming that those casualties are sustainable," Dunford told the British daily.
The casualty rate for Afghan forces surpasses that for US forces during the most deadly year for the NATO-led force in 2010, when about 500 American troops lost their lives in the war.
So far this year, about 100 US troops have been killed in action.
Afghanistan's 350,000-strong security forces are suffering a steep rise in attacks as the NATO mission winds down.
About 57,000 US troops are deployed in Afghanistan and the bulk of allied forces are due to withdraw in 2014, with tentative plans for a small contingent to remain afterward.
Milley said Islamist militants fighting Kabul remained resilient but were not in a position to score a decisive victory and take back control of the country after NATO forces depart.
"I do not think at this point in time, with the strength and capability of the Afghan security forces, that the Taliban or any of their allies have the capability to re-seize political power in the country of Afghanistan under current conditions," he said.