Prime Minister John Key has described Pete Bethune as 'downright ungrateful' for saying he felt abandoned by the Government following his arrest after boarding a Japanese whaling ship earlier this year.
The anti-whaling activist on Monday morning told media he felt the Government's reaction shows it has become Japan's 'fat little lapdog'.
Bethune, 45, arrived back in New Zealand on Saturday after a Tokyo court gave him a suspended two-year prison sentence on five charges relating to his protest action in February, and then deported him.
Speaking to media from Vietnam on Monday afternoon, Mr Key said Bethune should be more grateful for what Ministry of Foreign Affairs and Trade staff in Japan had done for him.
Bethune says he is disgusted at the way Foreign Affairs Minister Murray McCully has treated him, but he does not know whether there had been any influence in Japan from New Zealand's Foreign Ministry.
He says the Australian Government has shown more leadership on whaling than New Zealand's has.
Bethune's high-speed boat the Ady Gil was badly damaged in a collision in the Southern Ocean with the Shonan Maru 2 in January, and sank while under tow two days later.