Guangdong is ramping up an anti-prostitution campaign in the populous southern province to make it harder for sauna and massage parlours to offer sex services in secret.

Massage parlours and sauna houses, which are common venues for prostitution in China, must take measures to facilitate inspections, according to new provincial rules. They ban private sauna rooms inside massage suites, bar massage rooms from having doors with locks, and require the installation of windows. Parlours will also have to install CCTV cameras and keep footage for 30 days.

Guangdong officials are intensifying a crackdown on the sex trade that is called the “exterminate yellow” campaign because of the association the colour has with erotica and prostitution in China. It comes amid other campaigns by President Xi Jinping to clamp down on corruption and opulent spending.