London must start planning early if it is serious about hosting the 2012 Olympics, according to the head of the city's bidding effort.

Barbara Cassani highlighted the importance of early planning for the bid during a tour of Wembley Stadium yesterday.

"Start planning early and complete things as early as you possibly can," she said.

The comments from Ms Cassani, chair of the London 2012 bid, come amid ongoing speculation about Athens struggling to be ready in time to host the 2004 Olympics in the summer.

Ms Cassani said the London 2012 bid had already applied for planning permission for its Olympic Park plans in east London.

"We have started planning right now, before we have even been chosen."

Work is progressing ahead of schedule on Wembley Stadium, which is expected to open in early 2006.

A massive arch, the centrepiece for the new stadium, is to be raised over the site in the next few weeks.

Ms Cassani said the redeveloped stadium, which was a venue for the 1948 Olympics, was a sophisticated showpiece.

"Wembley combines the old and the new. It is an iconic world class venue and shows what we can do in this country."

The stadium will host the footballs finals if the 2012 Olympics are held in London.