Hong Kong pro-democracy protesters defied a warning by China’s President Xi Jinping and took to the streets again on Friday, as the political turmoil seeped out to London, where a territorial minister was confronted by masked demonstrators.

Protests have swept Hong Kong since June as many in the city of 7.5 million people have vented fury at eroding freedoms under Chinese rule.

Violence has escalated, and tensions have spread overseas, sparking friction between China and Britain, which governed Hong Kong until 1997.

Hong Kong Justice Secretary Teresa Cheng fell in London on Thursday after being surrounded by pro-democracy protesters, in the most physical confrontation involving a minister since the unrest began.