ISLAMABAD: The US ambassador in Pakistan Ms Anne W. Patterson Wednesday ruled out the presence of private US security firm Blackwater, adding that the US officials and programs in Pakistan are solely aimed at serving people and Government of Pakistan.

According to a statement issued from the US embassy, she said there is no secret operating base in Karachi or anywhere in Pakistan nor are US troops of any command busy with any secret activity in the country.

An article in a US magazine alleging Washington\'s collusion with Blackwater or any other contracting firm were equally baseless and false, the embassy said.

US government programs for Pakistan are open and transparent and function in partnership with the government of Pakistan, Ambassador Anne W. Patterson said in the statement.

US personnel and programs in Pakistan have only one purpose - to assist the government and people of Pakistan as they face the complex challenges confronting their nation, she added.