Beijing is to begin a clamp down on foreigners illegally entering, residing or working in the national capital to improve social security, according to a local authority announcement on Monday.

The campaign is scheduled to run from May 15 to the end of August, said a spokesman with the Beijing Municipal Public Security Bureau.

Police will comb communities believed to have large numbers of such aliens and mobilize the public to report them, as well as tighten reviews of visa applications, he promised.

Official data shows that Beijing sees nearly 200,000 foreigners every day, including 120,000 inhabitants. Police records reveal that foreigners without income, a permanent abode and a job are more likely to commit illegal acts in the city.

Beijing police reported earlier that a British man was detained on suspicion of assaulting a Chinese woman on the side of a road in Xuanwumen in downtown Beijing's Xicheng district on Tuesday night.

The man, intoxicated on the night of the incident, is a British national in China with a tourist visa. A recording of the incident uploaded to video-sharing site youku.com by an Internet user incurred public wrath.