A set of four Chinese stamps from the Cultural Revolution era has sold at auction in Hong Kong for more than $1.15m (£708,000).
The stamps, which were never issued for use, feature a design called Mao's 1968 Inscription to Japanese Worker Friends.

The set was bought by a collector in Hong Kong.

The 600-lot auction, which featured both pre- and post-revolutionary Chinese stamps and also issues from Taiwan, raised more than $12m.

The auctioneers here describe the level of interest and excitement in stamps from the People's Republic of China as breathtaking.

Many have increased in value by 200% or more in the last two or three years.

The block of four Mao stamps was never issued as the Japanese government objected to its design, fearing the reaction from its own population.

Other rarities included a strip of three stamps from pre-revolutionary China in 1897, and some of China's first stamps issued nearly 20 years earlier.

The high prices paid at a similar auction here last summer seem to have encouraged some collectors to sell, bringing to market some collections that have not been seen for years.

But the supply is not keeping up with demand.

Richer Chinese are always looking for new ways to invest their money.

Beijing's measures to try to cool the red-hot property market are making it harder for richer individuals to buy multiple properties.

The financial returns that some stamps are now producing are attracting a lot of attention.

Stamp collecting is also said to have a special place in Chinese culture, with the rarest examples regarded as cultural icons or treasures.