An Afghan police commander and several of his men killed three US soldiers in the southern province of Helmand, turning guns on them after inviting them to a dinner to discuss security, Afghan officials said yesterday.

The men – all American special forces members – were killed on Thursday night while attending a meeting in the Sarwan Qala area, in what appeared to be a planned attack by rogue Afghan forces.

A senior Afghan official said: "During dinner, the police commander and his colleagues shot them and then fled. The commander was in charge of local police in Sangin. It looks like he had drawn up a plan to kill them previously."

A spokeswoman for Nato-led forces in the country confirmed the incident but said it was too early to say whether it was a rogue shooting or due to insurgent infiltration.

"All we know is they were killed by an Afghan in a uniform of some sort," the spokeswoman said.

So-called green on blue shootings, in which Afghan police or soldiers turn their guns on their western colleagues, have seriously eroded trust between the allies as Nato combat soldiers prepare to hand over to Afghan forces by 2014, after which most foreign forces will leave the country.

According to Nato, there have been 24 such attacks on foreign troops since January in which 28 people have been killed, not including Thursday's attack.