Coffee chain Starbucks has agreed to pay more UK corporation tax, after a public outcry over how little it pays.

Kris Engskov, managing director of Starbucks UK, announced that the company would pay "a significant amount of tax during 2013 and 2014, regardless of whether the company is profitable".

One tax expert described the move as "unprecedented".

HM Revenue and Customs reacted by saying that corporation tax "is not a voluntary tax".