Miley Cyrus has hit back at criticism of her surprise engagement, and revealed she and fiance Liam Hemsworth aren't rushing down the aisle.

The former Hannah Montana star recently got engaged to Hunger Games actor Liam and some people have suggested that, at 19, Miley is too young for marriage. But according to the New York Post's Page Six, the star doesn't agree.

She told America's Marie Claire magazine: "Life is too short not to be with the person you want to be with."

Miley, who confessed it was a "complete surprise" when her 22-year-old boyfriend of three years popped the question, explained that the smitten pair are not planning to exchange their vows just yet.

She said in the mag's September issue: "I don't really care about the wedding or the piece of paper as much as I do the promise we've made to each other.

"And we want to have a long engagement."

Miley and Liam got engaged in May after the Australian actor proposed with a 3.5 carat diamond ring.