Kelly Macdonald has described her debut voice role in Disney-Pixar's Brave as "a real challenge".

The Boardwalk Empire star, 36, was promoting the Scottish animated film - in which she voices teenage heroine Merida - with co-star Kevin McKidd, director Mark Andrews and Pixar chief John Lasseter in Edinburgh, Scotland.

"It was a real challenge. It was a real learning curve. I always underplay everything but you can't get away with that in animation," she said.

"The teenage aspect wasn't a challenge - that came really quickly after 17 years," she added.

Kelly, who was born in Glasgow, admitted that flame-haired archer Merida is nothing like her.

"For me, this was so far removed from me that if it was a live-action film, I don't think I would even be in the casting," she quipped.

Kevin - who voices Lord MacGuffin and young MacGuffin - said he was "proud" to introduce his home dialect Doric to the world.

The 38-year-old from Elgin, Moray, said: "I am proud to bring that in. It was a lot of fun to speak in my crazy local dialect."

Kevin, who stars in Grey's Anatomy as Dr Owen Hunt, added: "I rarely get asked to be Scottish any more - I normally get to be American, so it was nice."

Brave, which will close the Edinburgh International Film Festival in June 30, opens in cinemas on August 17.