SAN JUAN, Puerto Rico — An abrupt announcement rattled members of a little-known UN agency based in Jamaica that has protected international deep-sea waters for more than 30 years.

The Metals Company in Vancouver said late Thursday that it is seeking permission from the U.S. government to start deep-sea mining in international waters, potentially bypassing the International Seabed Authority, which has the power to authorize exploitation permits but has yet to do so.