An ally of chief executive Leung Chun-ying called his ministers merciless and ignorant of history after the government failed to send representatives to receive activists who returned from the disputed Diaoyu Islands.
Lew Mon-hung, a delegate to the Chinese People's Political Consultative Conference, said the fact that no one from the government was present to welcome the activists who returned by air or sea was "most regrettable".
Seven of the eight activists landed on Diaoyu, the main island, to assert Chinese sovereignty over the islands in the East China Sea, which Japanese call the Senkaku Islands. The activists, four crew and two journalists accompanying them were arrested by Japan's coastguard.
"They took the risk to reach the island neither for personal gain nor the benefit of a small group of people, but for our nation, and that trumps the prejudice of political parties," Lew wrote in a statement.
"They risked their lives and even dared to go into the lion's den, and fortunately returned safely. But the Hong Kong government officials would not even come to receive them when they returned."
The chief executive was invited to join a welcoming party on Wednesday, but no government official attended.
Members of the Hong Kong-based Action Committee for Defending the Diaoyu Islands protested at the Japanese consulate yesterday against the decision to arrest the activists and those accompanying them.
The activists say they will sue the Japanese government for illegally arresting the seven men who landed on the island and planted the national and Taiwanese flags.
The eight activists, the crew of fishing boat the Kai Fung No2 and two journalists were deported following their arrest.
Chan Yue-nam, vice-chairman of the action group, has said it also plans to call on Beijing to address the Japanese government directly about the treatment of their colleagues.