The website of Japan's Prime Minister Shinzo Abe was rendered inaccessible on Thursday owing to a DDoS attack.

The hacktivist collective Anonymous is suspected of taking down the site in protest of the nation's starting up whale hunting after a decades-old international moratorium on the practice. In the past, Japan has claimed exemption for scientific study, but the departure last week of two Japanese whaling vessels en route to Antarctica revived international attention.

A tweet, claiming to be from an Anonymous member, took responsibility. The group was credited for its takedown last month of sites in Iceland, which has a similar whale hunting policy.

The PM's office as well as the Tokyo Metropolitan Police Department are reportedly investigating the attack.

The site has been restored.