[b]Three American soldiers have been killed in an apparent insider attack in eastern Afghanistan.

In a statement, Nato said a man in an Afghan army uniform turned his weapon on the international trainers.

The shooting is the latest in a string of attacks in which infiltrators or disgruntled Afghan police or soldiers have killed international troops working with them.

The killings threaten to shake the confidence and trust of the two sides as withdrawal of most international troops approaches in 2014.

Nato have given few other details of the latest attack - and it does not release the nationalities of casualties until their home countries announce them.

Taliban insurgents claim most insider attacks, but the international Coalition has said some of them are sparked by personal disputes.

Meanwhile, in the western province of Farah, an Italian soldier was killed and three others wounded when an attacker lobbed explosives into their armoured vehicle, Italy's government said.

The Defence Ministry said the attack came as the troops were returning to their base from training Afghan security forces.

The Taliban has taken responsibility for the attack, with spokesman Qari Yousef Ahmadi claiming that the attacker was an 11-year-old boy.

But Farah province provincial government spokesman Abdul Rahman Zhawandai said an adult male was seen throwing a grenade, then escaping by blending into the crowd at a nearby vegetable market.

Taliban insurgents have launched intense attacks across the country as Afghan forces take over most security responsibility ahead of foreign withdrawal.

Saturday's deaths brought to 16 the number of international troops killed in Afghanistan this month.

On Thursday, seven Georgian soldiers died in a truck bombing at their base in the south.[/b]

SOURCE: http://uk.news.yahoo.com/afghanistan-three-american-soldiers-killed-115359483.html#t7Ekbtb