A policewoman checks a bottle of liquid in a Beijing railway station on Monday, July 21, 2008.  

With the Summer Olympics right around the corner, Beijing is beefing up security in the city's four railway stations.

A 24-hour security screening is now conducted on luggage in the Beijing, Beijing North, Beijing South and Beijing West stations.

Policewoman guiding bomb-sniffing dogs are now also present at the railway security checkpoints, China National Radio reports.