TOKYO (AFP) - Japanese officials said on Wednesday that the number of bodies in a bizarre dog dumping case had reached nearly 70 animals, days after police launched a criminal investigation.

Authorities said they had found almost 30 more dead dogs, following the discovery last week of 40 canine corpses by a river in the eastern part of the country.

The newly discovered bodies were mainly small breeds, such as Chihuahuas and Toy Poodles, a local police officer said.

The site in Tochigi prefecture is some 20 kilometres from the original dumping site.

"The bodies are decaying badly," the officer said.

"Police are investigating a possible link between the case today and last week." Jiji Press news agency reported last week the police suspect an animal undertaker may have dumped the dogs, but authorities have only said they were "looking into various possibilities".