Tensions between Hong Kong residents and visitors from mainland China will not be tolerated, the city's leader said Monday as he confirmed a limit on the number of visits which mainlanders can make.

An influx of millions of Chinese visitors to Hong Kong has prompted rallies by residents angered by congested public transport and shop shelves emptied of daily necessities that are resold over the border.

At least 15 people were killed as a blaze engulfed a food market in China in the early hours of Wednesday, local authorities said.

The inferno took hold of the Rongjian Agricultural Wholesale Market in Shenzhen, which borders Hong Kong, the city's fire department said.