Image copyright disney via twitter

Disney has announced it will produce a sequel to its runaway hit Frozen, which last year became the highest-grossing animated film of all time.

The Oscar-winning picture made $1.27bn (£857m) at box offices worldwide, and led to record sales of related merchandise.

Frozen 2 will reunite the team behind the original feature, including director Chris Buck, writer Jennifer Lee and producer Peter Del Vecho.

The studio did not name a release date.

Shares in parent company Walt Disney were up by almost 4% following the news.

Toy-maker Mattel, which currently owns the license to sell Frozen products, saw its shares rise by almost 5%.

Image copyright AP Image caption Dolls based on the characters in Frozen have been flying off retailers' shelves

Last month, Disney credited the continuing success of toys based on Frozen for an "incredibly strong quarter".

Net income rose 19% to $2.2bn (£1.5bn) in the three-month period, with revenues up 9% to $13.4bn - both figures better than forecast.

In December, Frozen became iTunes' biggest-selling movie of all time, while the soundtrack sold more than any other album in the US in 2014.

Additionally, DVD and Blu-ray sales of the animation broke the three million mark on the first day of their release.