The British actor, awarded an MBE for his services to drama in 2012, called for ethnic minorities not to "stand on the sidelines of the British democratic system".
"We are part of it and our voices matter,” he said.
Harewood, who enjoyed a breakthrough as the CIA director in the acclaimed US drama series Homeland, said political disillusionment among minority communities was of stark contrast to attitudes across the Atlantic. "America has had affirmative action for many years, and that has physically changed the colour of US society," he told The Independent.
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"In America I'm hugely used to turning on my TV and seeing political analysts from the black community, financial analyst from the black community, politicians, generals in the army and captains of industry."
He added: "We don't have that here. I think it's been difficult for us to rise up the ladder. We simply don't get into those rooms where those jobs and opportunities are available to us."
Operation Black Vote of a poster featuring Sol Campbell, one of four black British stars appearing with white faces in a hard-hitting new campaign to encourage minorities to register to vote ahead of the general election. (Rankin/Operation Black Vote/Saatchi & Saatchi)
Harewood, 49, is spearheading a last-minute push to get black and ethnic minorities to register to vote ahead of next month's general election.
The Operation Black Vote campaign comes amid concern that the absence black and ethnic minority voters on May 7 could influence results in as many as 168 marginal seats. Nearly 30 per cent of Black Africans were not registered to vote in 2010, compared to seven per cent of white voters.
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Harewood, the first black actor to play Othello at the National Theatre, joins other black celebrities including footballer Sol Campbell, singer Tinie Tempah and Paralympic medallist Ade Adepitan in the campaign which sees each pose in photographs with their skin colour turned white.
The slogan claims: "If you don't register to vote, you're taking the colour out of Britain."
Harewood added that of the few current contenders of future Prime Minister from the black and Asian community, the Labour shadow business secretary Chuka Ummuna had potential. "I think he's hugely articulate. Whenever I see him he appears very comfortable. I often sit there and think to myself 'wouldn't it be exciting if he got on the ballot for the next leader of the Labour party?'"
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