The Labour Party's shadow Chancellor of the Exchequer John McDonnell speaks at the party's conference in Liverpool, Britain, September 24, 2018. REUTERS/Phil Noble

LIVERPOOL, England (Reuters) - Britain’s opposition Labour Party will demand companies demonstrate they pay their fair share of tax, its finance spokesman John McDonnell said on Monday.

McDonnell said some companies were avoiding paying their taxes “on an industrial scale”, denying the public money for services such as hospitals and schools.

“We’ll be demanding companies sign up to the Fair Tax Mark standards, demonstrating transparently that they pay their fair share of taxes,” McDonnell told his party’s annual conference.

“Make it clear and make it loud, the warning to the tax avoiders is: the game is over.”