Japanese fishermen will set sail on Monday to hunt whales commercially for the first time in more than three decades after Tokyo's controversial withdrawal from the International Whaling Commission (IWC) triggered outrage from environmental groups.

The planned hunts, while small and far from internationally protected ­waters, have also sparked anger in countries where whaling is considered outdated and harmful. 

But in Japan, whaling communities hailed the return of the practice, with Tokyo defending it as a tradition that should not be subject to outside interference.

For years, the issue of whaling was a diplomatic headache for Japan, which came under attack for exploiting an IWC loophole to hunt whales for "scientific" purposes.

Critics accused Japan of effectively carrying out stealth whaling, saying the hunts had no scientific value, while ­Tokyo continued to push for permission to resume commercial whaling outright.

But last year it announced it would simply withdraw from the IWC and no longer comply with its decades-old ban on commercial killing of the ocean ­giants.

The decision comes into effect from Monday, when a flotilla of ships that once carried out whaling for "scientific research" will set sail from the Shimonoseki port in western Japan.

Elsewhere, five small whaling boats from across the country will gather in Kushiro port in northern Japan and start hunting minkes for about a week in a symbolic event celebrating the resumption of the practice.

"We are very excited at the resumption of commercial whaling," Yoshifumi Kai, head of the Japan Small-Type Whaling Association, told AFP ahead of the departure. 

"My heart is full of hope."

Japan's decision in December to withdraw from the IWC sparked a firestorm of criticism from environmentalists and anti-whaling countries such as Australia, New Zealand and Canada.

It came after years of failed attempts by Tokyo to convince the IWC to allow it to resume commercial whaling, arguing that stocks of certain species were now sufficient to support renewed hunting.

The decision means Japan will end its most provocative expeditions, in ­protected Antarctic waters, and instead concentrate on commercial whaling of minke and other whales off its shores.

Japan has hunted whales for centuries and the meat was a key source of ­protein in the immediate post-World War II years when the country was desperately poor. But consumption has declined ­significantly in recent decades, with much of the population saying they rarely or never eat whale meat, and activists have pressed Japan to ditch the practice.