Chinese archaeologists are excavating sunken warships used by Zheng Chenggong and his followers to reclaim Taiwan from Dutch occupiers more than three centuries ago.

The ruins of Zheng's fleet were found near Dongshan Island in east China's Fujian Province in 2000. But as long as ten years before, local people had found bowls, plates and other porcelain wares with the seals of Zheng Chenggong.

Local fishermen said they can see rusty cannons at ebb tide.

The excavation began on June 6 and is scheduled to finish by the end of September. It may last longer, though, if the sunken ships are found to be still intact, said Chen Liqun, a cultural official in Dongshan County.

Chen said that archaeologists have yet to determine how many ships are under water.

More than 20 underwater archaeologists from the National Museumin Beijing are working in Dongshan. They have discovered broken china pieces, cannonballs, grenades, iron blocks and muddy sand mixed with gun powder.

Archaeologist Lin Guo said that the ruins are located in a geologically complex area. Tides and typhoon also add to the difficulty in excavation.

Lin said that what they have found can help prove that Dongshan served as an important military training base for Zheng's troops.

Zheng Chenggong was born in 1624, the year Dutch invaders occupied Taiwan. His troops drove the invaders off the island in 1662. Zheng died on the island in the same year.

Zheng is considered a great patriot by the Chinese people.