In a bid to promote folk efforts in retrieving relics lost overseas, the China National Philatelic Corporation issued a set of stamps Tuesday featuring the heads of 12 stolen bronze animals from Yuanmingyuan Garden.

Each set consists of 12 stamps featuring bronze heads of 12 sculptures formerly guarding a mansion in Yuanmingyuan Park (also called the Summer Palace) in northwest Beijing, the sculptures have animal heads and human bodies.

Yuanmingyuan was looted and burned down by Anglo-French Allied forces in 1860, and the heads were removed by intruding foreign troops 145 years ago.

Four bronze heads -- the cow head, tiger head, monkey head and pig head -- have been recovered, and those stamps bear their photograghs.

But stamps of the other eight heads use artists' renderings as the heads themselves -- including the mouse head, rabbit head, horse head, dragon head, snake head, rooster head, dog head and sheep head, which remain missing overseas.

"It's a pity, but could remind people to work harder still to retrieve the other treasures lost and help the 12 animals reunite at their homeland," said Zhang Yongnian, director of China's Lost Cultural Relics Recovery Fund, a non-governmental organization set up to retrieve Chinese relics lost overseas.

The returned treasure and the other eight bronze sculptures feature the 12 animals symbolizing each of the 12-year cycle in which people are born.

One and two thirds million cultural relics are housed in more than 2,000 museums in 47 countries worldwide, accounting for just 10 percent of all lost Chinese priceless cultural treasures. Most of the lost treasures are owned by private collectors.