US Defense Secretary Leon Panetta voiced concern on Tuesday about the so-called “green-on-blue” attacks in Afghanistan.

US Defense Secretary Leon Panetta voiced concern on Tuesday about the so-called “green-on-blue” attacks in Afghanistan.

Calling the attacks in which Afghan troops kill NATO occupation as “insider attacks”, Panetta said he was "very concerned" about the rise in these attacks and the impact they are having on cooperation with Afghan allies.

"Our enemies have attempted to undermine the trust between the coalition and the Afghan forces and in particular they have tried to take credit for a number of so-called green-on-blue or insider attacks that are taking place this fighting season," Panetta told a press conference.

"Make no mistake about it, I've been very concerned about these incidents ... because of the lives lost and because of the potential damage to our partnership efforts," he said.

The Taliban are "resorting to these kinds of attacks to create havoc" because they have been unable to regain any lost territory, the defense secretary added.

According to NATO figures, 37 members of the International Security Assistance Force (ISAF) have died in 27 such attacks so far this year.