KABUL (Reuters) - A man wearing an Afghan police uniform has shot dead two U.S. servicemen in Afghanistan, NATO said on Thursday.

The assailant turned his weapon against the forces in Uruzgan province, it said in a statement.

"Insider" attacks on Western forces have undermined trust between coalition and Afghan forces as NATO prepares to withdraw most combat troops at the end of 2014.

At least 54 members of the NATO-led International Security Assistance Force have been killed this year by Afghans wearing police or army uniforms.

(Reporting by Hamid Shalizi; Editing by Alison Williams)