Keira Knightley: Doing something morally wrong could make you Prime Minister

Keira Knightley has joked that doing something morally wrong might lead to becoming Prime Minister.

The actress has delved into the debate about whistle-blowing and espionage for her latest film Official Secrets.

Ms Gun revealed that the US had been eavesdropping on diplomats from other countries.

Knightley, who plays the whistle-blower, said that far from being punished for wrongdoing, many are rewarded.

She joked: "You might actually get away with it, and progress.

"You could actually be promoted and rewarded - and be prime minister."

The actress hopes her latest film, based on the actions of Katharine Gun, will explore these areas of moral ambiguity.

She believes the issue of whether whistle-blowers should be punished or rewarded is an important one.

Knightley said: "How much do we want our secret services to be morally accountable for their actions, how much is that possible, should people be whistle-blowing, should that information come out?

"Would I be brave enough? Would I do right to do the same? Or would I just do what I was told?

"I don't know what the answer to that is, but I find all of the answers to those questions really interesting."

Official Secrets is in cinemas from Friday October 18.