Islamabad, Aug 14 (IANS) The US has expressed concern over Americans' harassment in Pakistan and sought withdrawal of no-objection certificates required for US envoys' movement. This came as an American aid expert was kidnapped by gunmen in Lahore.

On Saturday, US senator John McCain called on Pakistan's Chief of Army Staff General Ashfaq Parvez Kayani and discussed ways to improve Pak-US relations besides joint cooperation for counter terrorism efforts, Geo News reported.

During the meeting, McCain mentioned his concerns about Americans being harassed in the Pakistan and withdrawal of the requirement of NOC for the movement of US envoys, said the Inter Services Public Relations (ISPR) of Pakistan Defence forces.

On Saturday, about a dozen gunmen abducted a US national after breaking into his house in a locality in Lahore.

The American aid expert was kidnapped after eight gunmen stormed through the backdoor of his house and overpowered his guards, police said.

As per the US embassy, the man, who police said was in his 60s, had been identified as Warren Weinstein and that he worked for a private company.

Earlier this week, the US had issued a travel advisory for its citizens, saying Americans including aid workers and journalists were falsely being identified as spies in Pakistan, a media report said.