BEIJING - China's police and cultural authorities have jointly issued a circular calling for tightened museum security after three theft and robbery cases occurred in the country this year.

The cases include a May theft at the Palace Museum in China's capital, in which several exhibited items on loan from a Hong kong-based museum were stolen.

"People who have been encouraged by the high profits that can be attained through the theft and smuggling of ancient relics tend to set their targets on various museums," said a circular jointly released Tuesday by the Ministry of Public Security and the State Administration of Cultural Heritage.

The circular said that police and cultural authorities should examine museum security systems and improve training for museum guards.

Museums should make emergency response plans and conduct emergency drills every six months to improve their ability to handle thefts, according to the circular.

Police and cultural authorities will carry out security checks in museums before the end of this year, suspending the operation of museums with security flaws, according to the circular.