The eight young elephants were secretly transported from Mahidol University's animal hospital in Sai Yok district to the U-Tapao International Airport in Chon Buri on Saturday night.

The convoy was guarded by about 100 police and Army officials who blocked off animal rights activists who got wind of the move and went to observe it, said Suraphol Duangkhae, secretary-general of the

Wildlife Fund Thailand.

Four of the elephants were flown away in a Russian cargo plane yesterday while the others are being kept in a small forest behind the airport.

The elephants are to be given to two zoos in Sydney and Melbourne under an exchange agreement called the "Joint Cooperation in Captive Animal Management Programmes between Australia and Thailand".

Originally scheduled to take place in June, the transfer was halted temporarily after activists in Kanchanaburi, where the elephants were kept originally, blockaded the move.

Pinan Chotirosserani, head of the Kanchanaburi Conservation Group, said he tried to follow the convoy of elephants on Saturday night but could not reach the airport in time.

"As soon as the trucks entered the airport, the gate was closed and guarded by about 20 police and Army officers," Pinan said.

The airport has been declared off-limits to outsiders until Thursday, he said.

Pinan said the activists now planned to protest in front of the Australian Embassy in Bangkok instead.

"The transfer of the elephants goes against the assurance that the Natural Resources and Environment minister and CEOs of the Australian zoos gave us that DNA tests would be conducted on the elephants to confirm that they were born in captivity, not in the wild," Suraphol said.

Animal welfare activists believe the elephants are from the wild, which would make their export a contravention of the Convention on International Trade in Endangered Species (Cites).

He said the elephants' transfer was suspicious as it took place just before the activists' planned complaint to the Administrative Court today.

Activist Prasarn Maruekpitak said the secretive transfer was because the government urgently wanted to get four koalas in return from Australia to show at the Chiang Mai Night Safari.

Soraida Salwala, secretary-general of Friends of the Asian Elephant Foundation, yesterday released an open letter condemning the Thai government for sending the animals overseas.

The letter expresses the activists' sorrow to Thais for failing to protect the elephants, which are a national symbol.