On Monday Australia and New Zealand urged a Japanese whaling fleet to come back to port as it headed for the Antarctic in order to hunt more than 1,000 whales.

The fleet left on Sunday from the Shimonosek port in order to kill 50 humpback whales. This is the first hunt of whales of this scale since 1963, when they were put under international protection.

The fleet will also hunt 935 minke whales and up to 50 fin whales. According to Japan's Fisheries Agency this is the largest-ever scientific whale hunt and it will lasts until April.

Greenpeace said that the Esperanza, its ship, was searching south of Japanese territorial waters for the fleet, the Associated Press reports.

Expedition member Dave Walsh said: “It's a large ocean, but we're going to track them down.”

According to Greenpeace, the radio transponders were turned off by the fleet so that it would not be found. This accusation was denied by Hideki Moronuki, head of the whaling section at Japan's Fisheries Agency.

The hunt is criticized by Anti-whaling nations.

New Zealand's Prime Minister Helen Clark said: "It would just be better if the Japanese stayed home and didn't come down under the guise, the deception, the claim that it is scientific whaling when they want to take a thousand whales.”

The Australian government expressed its disappointment regarding the fleet’s departure.

Foreign Minister Alexander Downer and Environment Minister Malcolm Turnbull said: "The government again appeals to Japan to reconsider its position on this inhumane practice."

Japan says that the reason for killing whales is that it needs to conduct research on their reproductive and feeding patterns. The number it kills doesn’t threat the overall population.

Scientific whale hunts are allowed by the International Whaling Commission, but according to critics Japan uses it as a cover for commercial whaling.