Mark Wallinger's winning design for the Ebbsfleet Landmark Project

Permission to build a giant white horse in north Kent runs out next week - but those behind the controversial project are hoping to be given more time.

Artist Mark Wallinger won the Ebbsfleet Landmark Project in February 2009 with his design of a white horse to go on land between the A2 and Springhead Park.

Four years later, it still has not been built, but Ebbsfleet Landmark Project Ltd and Ebbsfleet Investment have not given up on the idea.

Planning permission was granted by Gravesham council several years ago, but the project - which has been dubbed the Angel of the South - has to be privately funded and Mr Wallinger has not yet managed to raise the £12-15m required.

Artist Mark Wallinger in 2009 with his winning design

Mr Wallinger unveiled a life-sized sculpture of a racehorse outside the British Council's headquarters in London earlier this month in an attempt to encourage private investors to come forward.

Planning permission runs out in April and an application for renewal has been submitted. It is not known when it will be considered.

The Ebbsfleet Landmark Project began in 2007 to provide a high-profile marker up to 160ft high for Ebbsfleet Valley, the Gravesham and Dartford communities and the north Kent region.

The horse will be one of the biggest artworks in the UK, comparable in scale to the Statue of Liberty.