North Korea is demanding the return of the crew and a ship seized by Panama with a haul of weapons from Cuba on board.

Panamanian authorities say it's going to take up to 10 days to unload the vessel because its electrical system was disabled by the crew.

Some 350 police and customs officers are swarming over the ship.

It has four storage areas, each with six containers.

So far only one area's been opened up, revealing missile equipment, MiG fighter jets and other arms.

Panama's security minister says the matter's being handed over to the United Nations.

A team of U.N. investigators is expected to arrive in Panama in early August once the vessel's unloaded.

Officials have found more containers they suspect might conceal armaments.

Cuba said the weapons are obsolete Soviet-era ones it was sending to North Korea for repair.