A threatening letter has been sent to a whale museum in Taiji, Wakayama Prefecture, demanding that local fishermen halt controversial drive hunts of dolphins, police said Thursday.

The letter, handwritten in Japanese, said, "Stop drive hunts of dolphins now!" and "I cannot contain (my anger) even if I tear (dolphin hunters) limb from limb." The writer also warned local fishermen to beware of traffic accidents.

A museum employee found the letter on Oct. 13 and reported it to a local fishery association, which informed police the following day. Police said they are looking into the case.

A Japanese newspaper article on drive hunts was also enclosed in an envelope that bore the name of a man and an address in Osaka Prefecture.

In the drive hunts, fishing boats herd dolphins and other small cetaceans into coves where they are caught or slaughtered, a method that has sparked criticism both in Japan and abroad.

Yoshifumi Kai, a senior member of the fishery association, said he understood there were various opinions about the hunting method, but it was "irritating" to receive a threatening letter.