BEIJING, Sept 7 (Reuters) - Beijing has launched a month-long crackdown on unlicensed beauty parlours and other common fronts for prostitution and gambling to sanitise the city ahead of a key Communist Party meeting next month.

Unregistered karaoke bars and bathhouses would also be targeted in a blitz across the city launched by 11 government departments, Friday's Beijing News reported.

"One third of the prostitutes detained by police in Beijing this year have come from these illegal beauty parlours," the paper quoted an unnamed police official as saying.

"These salons make up 50 percent of all the prostitution dens in Beijing."

Police have also instructed China's growing ranks of property owners not to rent out their homes to people who "stay out late" and have "irregular lifestyles", the China Daily said in a separate report.

The advice comes a week after Shanghai housing authorities drafted rules urging landlords not to rent rooms to unmarried couples and gays.

China has launched a string of campaigns aimed at stamping out crime and socially destabilising elements in the months leading up to the 17th Party congress, a five-yearly meeting where key leaders are chosen and policy direction fixed.

Other campaigns have included stripping highways of billboard advertisements for luxury goods that might fuel discontent among Beijing's poor, and cleansing local airwaves of "vulgar" and unpatriotic content.