Iceland says whales have become so abundant in its waters since a worldwide moratorium on commercial whaling that they are threatening stocks of fish, including cod.
But the International Fund for Animal Welfare (IFAW) says there is no scientific basis for the operation, and that Iceland cannot use science to camouflage its desire to resume commercial whaling.
Iceland's tourism industry has also criticised the hunt, fearing it could damage the country's image, and threaten the increasingly popular whale-watching business.
However, polls show three-quarters of Iceland's 290,000 population supports the resumption of whaling.
The environmental organisation Greenpeace has sent its flagship Rainbow Warrior on a mission to Iceland.
The ship, which campaigned against Icelandic whaling on its maiden voyage in 1978, is due to arrive in two weeks.