Three Pakistani men will be prevented from giving evidence to Parliament regarding Britain's alleged role in CIA drone strikes after they were refused entry to the country.

The men, including Noor Khan, who is currently suing Britain over its alleged role in a CIA attack which killed his father, had been invited to address the all-party parliamentary group on drones yesterday.

Also due to address the meeting was Kareem Khan, whose son and brother were killed in a drone strike on New Year's Eve 2009.