Representatives of the Kanchanaburi Conservation Group brandish protest placards in front of the Australian Embassy yesterday.

Wildlife Fund Thailand (WFT) secretary Suraphol Duangkhae said the protest would test Australia's sincerity.

He was among 20 NGO leaders attending the demonstration.

Suraphol called for DNA tests on the elephants to determine if they were domesticated or wild. He also demanded that four elephants flown to Australia on Sunday be returned.

WFT was "surprised" at a statement from Natural Resources and Environment Minister Yongyuth Tiyapairat that described the government's controversial decision to export eight young elephants to Australia as "an expression of goodwill". "Why was goodwill cited after the delivery. I am surprised," he added. He also questioned Yongyuth's claim that calves born to the elephants would belong to Thailand.

The four elephants were prepared for their journey at U-Tapao naval base in Rayong and departed for Australia via the Cocos (Keeling) Islands at 11pm.

Yongyuth reacted to allegations that Bt45 million had been paid to secure the elephant deal saying "it's another issue, but I don't think any official has broken the law.

"It's goodwill in a similar way to China [lending] two pandas to us," Yongyuth said in response to growing complaints about the deal from animal rights activists and conservationists.

The activists have threatened to petition the Administrative Court.

Yongyuth said it was legal to export the elephants under an exchange programme that would see koalas being sent here.

He said the activists could fly to Australia and conduct DNA tests if they wanted to find out whether the elephants were from the wild or not. Under Thai law, elephants must be domesticated before being exported. "We have already checked that these elephants were born in captivity," said Yongyuth.