A Japanese salvage ship on Wednesday raised the suspected spy ship that sank in the East China Sea in December during a firefight with Japan Coast Guard vessels.

A gigantic crane ship chartered by the coast guard brought the wreck up from some 90 meters under the surface, revealing a 30-meter-long, 180-ton vessel equipped with a set of outward-opening double doors on its stern -- a feature common to North Korean spy ships identified in the past.

Intelligence sources said the doors might be hiding a space used to hold small submersible craft capable of taking spies to shore.