U.S. military officials said yesterday they believe Iraq has been seeding Kuwaiti territorial waters with new Iraqi-made mines that have recently begun floating into international shipping channels.

American and allied warships and helicopters patrolling the international waterways south of Kuwait have spotted 14 mines since Dec. 21 floating in international shipping lanes, Pentagon officials said.

While the Defense Department officials have reported publicly that some mines have been discovered in the waterways in the past few weeks, they had said they did not believe the mines were laid by the Iraqis.

"Now we firmly believe they were laid by Iraq inside Kuwaiti territorial seas," said one Pentagon official. "We believe they were moored and broke loose and drifted down the gulf with the current."

Officials said the mines appeared to be recently manufactured and newly laid because no marine encrustations had yet formed on the spherical weapons.

The mines are also said to be powerful. When a demolition team blew up one of the mines, it sent a plume of water gushing 200 feet into the sky, one official said.

Defense Department officials said some government authorities have raised questions as to whether Iraq is in violation of international law by refusing to notify mariners of the mine fields and the possibility of untethered mines floating into shipping channels.

Iraqi officials have expressed public concern over the possibility of a U.S. Marine amphibious attack on the shores of Kuwait in the northern Persian Gulf. U.S. officials said the mines likely have been seeded to help deter such an attack.

Mines laid by Iranian forces during the eight-year war between Iraq and Iran created major problems for warships and trading vessels plying the Persian Gulf. During the first U.S. escort mission of reflagged Kuwaiti tankers through the gulf, the tanker Bridgeton hit a mine that caused serious damage to the ship. The American guided-missile frigate USS Samuel B. Roberts was nearly destroyed when a mine exploded under its hull in the gulf during an escort operation.