The British Retail Consortium (BRC) has warned London Mayor Boris Johnson he must not rush into introducing laws which force retail developers to give space to “affordable” shops.

Johnson is considering using Section 106 planning powers to force lower cost premises to be provided on new retail sites.

The BRC believes that, instead of helping smaller retailers, the initiative may undermine existing retailers of all sizes.

“The mayor needs to think through all the implications of forcing any new obligation on developers,” said BRC director-general Stephen Robertson.

“With businesses already facing some of the toughest conditions in decades, an obligation to provide units at below-market rents could further undermine retail investment by making some developments unviable.”