Museum burglars bring to mind a Sean Connery type sneaking through a ceiling.

Museum security was usually thought to be so good that those looking to steal art would be forced to come up with ever more elaborate plans.

Clearly that is not the case.

A thief broke into the Palace Museum, or the Forbidden City, in Beijing on Sunday by knocking a hole in a wall and seven rare items from a Hong Kong collector that were on show at the museum were stolen. Two other items were damaged.

The suspect escaped even though the museum's guards saw him.

To all heritage-conscious Chinese - and for that matter, culture lovers around the world - such a previously inconceivable theft must come as a shock.

The museum was thought to be well-guarded, all the thieves who have previously tried to get loot from the Forbidden City have been caught. It had security personnel with more than 100 patrol dogs, plus at least 1,600 anti-theft alarms, 3,700 smoke detectors and 3,700 cameras.

But the break-in at the museum makes the guards, animals and equipment a joke.

Security dealers are helping museums by installing better perimeter defenses including motion detectors, body-heat sensors and a host of other devices. In some museums video surveillance and access control measures are used to address theft from visitors.

Good devices however, are not available for every museum.

A bronze mirror that is more than 1,600 years old was stolen from the Dunhuang Municipal Museum in Northwest China's Gansu province during opening hours in August 2008.

Zahi Hawass, the secretary-general of Egypt's Supreme Council of Antiquities, said, "If you want to protect your home from theft, don't leave the door open."

The theft in the Palace Museum should be a reminder for other museums to introduce an effective security system headed by trained guards and supported by better surveillance equipment.

The Palace Museum apologized for the loss. Pictures of the stolen items have been published so as to prevent them from being offered for sale on the international market.

But we also need to keep our eyes on the auctions to trace whether they sell the stolen pieces from the Museum.