Homeland star David Harewood is urging British fans to become organ donors after the death of a close friend.

The British actor, who played Central Intelligence Agency (Cia) executive David Estes in the U.S. political thriller, was present when his pal passed away, and the experience moved him to join a campaign for the U.K.'s National Health Service (Nhs).

Harewood, who is an organ donor himself, joined a number of famous faces including business tycoon Sir Richard Branson, to raise awareness for the National Transplant Week campaign Pass It On, which started on Monday (08Jul13).

In a promotional video for the drive, Harewood shares his moving experience and implores viewers to lead by his example and sign up as an organ donor.

He says, "When you actually see (death), it's such a powerful thing. I suppose, I thought he would just look like he was sleeping... but that something special is missing and that's when it hits home. That's when you realise they're dead. I'll never forget that sight."