TOKYO (AFP) - Japan's coastguard expelled hundreds of North Korean fishing vessels from its waters this summer, officials said on Thursday (Aug 31), as tensions soar in response to Pyongyang launching a missile over its neighbour.

The agency said it fired water cannon at some boats whose crew refused orders to leave the Yamato Banks, a rich fishing ground in the Sea of Japan (East Sea), adding that the expulsions started in mid-July.

It was the first time the coastguard revealed it has been booting the North Korean ships from Japan's exclusive economic zone (EEZ).

The announcement came two days after North Korea launched a missile over Japanese territory, drawing global condemnation and stoking calls for more sanctions against the regime.

Japan's coastguard said it issued at least 820 warnings to North Korean boats trawling illegally in its economic zone, which extends some 200 nautical miles from its coastline.

The agency added that a particular boat might have received more than one warning.

"Since mid-August, we haven't seen North Korean fishing vessels in waters around the Yamato Banks," an agency official said.

Every year, badly damaged boats - sometimes with rotting corpses inside - wash up on Japan's shores.

They are believed by some experts to be North Korean fishing boats that had ventured far from their own coast in search of bigger catches to alleviate the impoverished nation's regular food shortages.

In July, Tokyo said it has lodged a protest with Pyongyang after one of its patrol vessels was chased by an apparently armed fishing boat believed to be from North Korea within Japan's EEZ.