TOKYO — The Japanese authorities said they were investigating whether the hacking group Anonymous was behind a computer attack that shut down Prime Minister Shinzo Abe’s personal website on Thursday.

A person claiming to be part of the group of activist hackers claimed responsibility for disrupting access to the site, saying in a message posted on Twitter that the attack was carried out in retaliation for Japan’s resumption of whale hunting in the Antarctic.

Hackers linked to Anonymous have targeted websites related to whale and dolphin hunting before. The group claimed responsibility last month for the shutdown of several government sites in Iceland, another nation that practices whaling.