A respected Conservative lawmaker says she's switched sides in Britain's European Union debate and now supports staying in the bloc because she says the "leave" side has been lying about how much money Britain pays the EU.

Sarah Wollaston, a doctor who heads the House of Commons health committee, says a claim that Britain sends the EU 350 million pounds ($505 million) a week is "a financial lie."

The figure does not include Britain's rebates. The net U.K. contribution is about half that.

The "leave" group has emblazoned the figure on its campaign bus and claims leaving the EU would mean the money could be spent on Britain's overburdened National Health Service.

Wollaston said Thursday it's "shameful" to build a campaign on deceit, and leaving the EU would cause "economic turmoil."