People who mail parcels to Beijing and five other Olympic co-host cities on the Chinese mainland will have to provide their identity cards at the post office counter as from July 20.

The rule, in effect until September 20, is to ensure safety during the Olympics and Paralympics, the State Post authority said in Beijing Wednesday.

The co-host cities are Tianjin, Shanghai, Qingdao, Shenyang and Qinhuangdao.

Parcels will also be opened and checked for safety.