Sydney, Feb 20 (DPA) Prime Minister Kevin Rudd's surprise threat to take legal action to stop Japan killing whales in Antarctica has drained goodwill from the first visit to Australia by Tokyo's new top diplomat.

Foreign Minister Katsuya Okada, in the job for just five months, meets Rudd Saturday amid heightened conflict over whaling.

The pledge to take Tokyo to the International Court of Justice came last week after Rudd was hammered for not delivering on a campaign promise before the November 2007 election that he would take legal action unless whaling stopped.

The threat, made as Rudd falters in the opinion polls and the country readies for an election later this year, was written off by most analysts as ploy to placate his domestic critics rather than to confront Japan.

But Okada is likely to warn Rudd that the spat over whaling could imperil good relations between important trading partners Australia and Japan.

'It is imperative that we seek a diplomatic solution to this issue through understanding of culture and position of each party,' Okada said in a statement prior to his arrival in Sydney. 'We should not take an emotional approach.'

Japan uses a loophole in the 1986 whaling moratorium to continue whaling under the guise of scientific research. According to conservation organisation Greenpeace, it has killed more than 9,000 minke whales over the last 22 years.

The threat of legal action came after clashes between international protest group Sea Shepherd and the Japanese whaling fleet.

Sea Shepherd's Ady Gil was holed in a collision last month and sank while being towed to port for repairs. Last week, Sea Shepherd activist Steve Bethune boarded a Japanese vessel and is being held by the whalers until the fleet returns to Japan next month.

Japan has said it will press charges of piracy against the New Zealander that could see him imprisoned for three years.

Sea Shepherd's Australia manager, Benjamin Baldwin, said Bethune's detention would not deter protesters.

'We would like to remind minister Okada that no matter what the outcome of the talks with the government are, if he intends to continue this barbaric slaughter, Sea Shepherd will always be there,' he told a group of 30 demonstrating against whaling outside the Japanese embassy in Canberra.