Ten thousand small firms in London are being hit by a stealth rise in business rates this year.

Government figures reveal that there has been a large fall in the number of companies that are exempt from paying a rates supplement to fund Crossrail following a revaluation in April.

Until the recent changes just under a quarter of a million SMEs in the capital fell below a rateable value of £50,000 and therefore didn't pay a supplament. But the value of property prices was recalculated at the peak of the property boom, meaning many firms are now over the limit.

"It's a disgrace that at the time London businesses need support they are getting higher taxes," said Shadow London minister Justine Greening.