Japan has rejected condemnation over its slaughter of 122 pregnant whales in Antarctic waters, saying the "scientific" work confirmed the animals were fertile.

The annual bloodbath in the Southern Ocean made international headlines last week after Fairfax Media reported the gruesome results. The hunt takes place in Australian whale sanctuaries in contravention of international law.

Japan says it annual slaughter of minke whales is required to learn about the Antarctic marine ecosystem. Credit:AFP

The Japanese fleet killed 333 Antarctic minke whales. In addition to the 122 pregnant animals, 114 were juveniles.

In a statement on Monday, the Japanese embassy told Fairfax Media it did not specifically target pregnant whales, even though they comprised more than 95 per cent of the mature females killed.