Work to build a multi-million pound art gallery in Kent is finally under way, but councillors have admitted the completion date has been put back again.

The long-awaited Turner Contemporary, to be built close to Margate harbour, will not be finished until 2011 - two years later than originally pledged.

KCC leader Cllr Paul Carter said the £17.5 million building will boost regeneration and encourage a greater sense of pride in the area.

But Cllr Richard Nicolson, leader of the Thanet Labour group, criticised the delay, saying: "A couple of years ago we were told the gallery would be open by 2009 and cost not a penny more than £15million."

Cllr Carter joined other senior officials for a groundbreaking ceremony on Tuesday, at which local schoolchildren carried large mirrored letters spelling out the words "The sun is God".

The phrase is a quotation from former Margate artist JMW Turner, after whom the gallery is named.

Thanet council leader Sandy Ezekiel said the event represented an important milestone in the project.

He added: "It's a fantastic day for Margate, for Thanet and for the whole of East Kent. It really is an occassion to remember and an event to mark down in history.

"The Turner Contemporary will see Margate reborn. The town's had some chequered history over the last 20 years or so, but we now have a clear direction of where we want to go."

Kent-based contractors R Durtnell and Sons have been tasked with building the gallery, designed by award-winning architect David Chipperfield.