The Earth Liberation Front (ELF) is part of a growing band of activists who are taking to extreme measures to protect the environment and animal rights.

In recent times, they have attacked biomedical laboratories, sent death threats to scientists, harassed whaling vessels and even desecrated graves, according to reports in Britain's Daily Telegraph.

In Britain, groups such as the Animal Liberation Front - a sister organisation of the ELF - waged a campaign of arson and vandalism during the four years it took to build a controversial £20 million (S$56 million) biomedical laboratory at Oxford University.

The laboratory, on which work started in 2004, was to house all of the university's existing animal-testing labs.

But the saboteurs did not confine their attacks to the new building, striking as well at university staff, students and independent contractors working in other fields.

A college boathouse was set ablaze, an explosive device was found in a sports pavilion and a number of professors who worked with animals received death threats and letter bombs.

In 2006, in Britain, the remains were found of a woman whose grave had been desecrated 19 months earlier by animal rights activists.

Mrs Gladys Hammond, who was 82 when she died, had a son who owned a farm breeding guinea pigs for medical research.

More recently, Japanese whaling ships have come under attack from an Australian group called the Sea Shepherd Conservation Society.

A formal complaint was made to Australia by Japan earlier this month after members of the group hurled chemicals and bottles of rancid butter onto the whaling ship Nisshin Maru in the Southern Ocean.

Three members of the Japanese vessel's crew had to be treated for irritation to their eyes from the rancid butter, which turns into butyric acid.