Keira Knightley has revealed she had to speed up her acting for new film Begin Again, which was shot on location in New York.

The British actress - who plays an aspiring singer-songwriter in the romantic comedy, co-starring Mark Ruffalo and Adam Levine - admitted she was a little taken aback by how impatient New Yorkers are about films being made on the streets of their city.

Keira explained: "The thing about New York is, if you film anywhere else in the world, people are a little bit curious, they're excited, but generally if you just go 'Can you get out of the shot?' they go 'Yeah, yeah. Absolutely.'

"In New York if you say that they go 'NO! Get out of the sidewalk!'

"So the biggest challenge was to get out of the way before people started shouting at us."

Fellow Brit James Corden play's Keira's character's best friend in the film, and the actress admitted she found it hard not to laugh working with the comedian.

She said: "A lot of this film is improvised and he is the master of that and so he did certainly throw a load of curve balls at me, which was just really fun.

"I think that was the vibe of the film really, it was very spontaneous, it's kind of got that energy. A lot of the way we were filming was just to go around in vans and jump out and film a scene as quickly as possible before anyone noticed.

"So a lot of the improvisation helped with the spirit of the thing."