A gunman dressed in Afghan security uniform killed three U.S. soldiers in the southern province of Helmand, Afghan media reported, quoting NATO officials, according to RIA Novosti.

The three soldiers, who were special forces members, were shot dead while attending a meeting in Sangin District late on Thursday, August 9 the Khaama Press newspaper said.

The attack was the latest in a series of so-called green-on-blue shootings, in which men wearing Afghan police or military uniform turn their guns on foreign troops, and the third such case in the past few days.

On Thursday, an Afghan soldier turned his weapon on NATO allies in the eastern Laghman province. No ISAF soldiers were killed in the attack. The gunman was killed in return fire.

On Tuesday, a U.S. solider was killed and two others were wounded when two men in Afghan army uniforms opened fire on their allies at a military base in the eastern Paktia province.

There have been 24 such attacks on foreign troops since January in which 28 people have been killed, according to the Khaama Press report which quoted NATO statistics. Last year, there were 21 attacks in which 35 people were killed.