An Afghan policeman has opened fire on Nato soldiers in the fifth such attack in a week, but this time no-one was killed.

An initial investigation indicated attacker was an Afghan police officer

The Taliban claimed responsibility for the shooting in the eastern province of Nangarhar, saying the attacker was a police officer who had been in contact with them before the assault.

A recent rash of “green-on-blue” attacks, in which Afghan security forces or attackers wearing their uniforms turn their guns on the coalition troops training them, has raised worries about a deterioration of trust between the two sides, just over two years before Nato is set to turn over security to local forces and pull out most of its troops.

Taliban insurgents are eager to exploit such a rift.

The trend also raises renewed concern that insurgents may be infiltrating the Afghan army and police, despite intensified screening.

Nato said an initial investigation indicated the attacker was an Afghan police officer, though the man was wearing civilian clothes.

He said there were no Nato deaths but would not say if any international service members were wounded in the attack.

At least one Afghan intelligence agent was wounded in the shooting and the gunman escaped, according to according to the Nangarhar provincial governor.