Anti-whaling activists intercepted Japan’s harpoon fleet far north of Antarctic waters on Sunday, they said, with the help of a military-style drone.

Sea Shepherd Conservation Society spokesman Paul Watson said the unmanned long-range drone, launched from the anti-whaling ship the Steve Irwin, had located the Japanese fleet and relayed the coordinates back to the activists.

Watson said Sea Shepherd, a militant activist group which regularly shadows and harasses the Japanese whalers, had caught up with the fleet at 37 degrees south, 1,000 miles (1,600 kilometres) above Antarctic waters.

“This is going to be a long hard pursuit from here to the coast of Antarctica,” said Watson.