PANAMA CITY (AP) — Cuba said military equipment found buried under sacks of sugar on a North Korean ship seized as it tried to cross the Panama Canal was obsolete weaponry from the mid-20th century that it had sent to be repaired.

Panamanian authorities said it might take a week to search the ship, since so far they have only examined one of its five container sections. They have requested help from United Nations inspectors, along with Colombia and Britain, said Javier Carballo, Panama’s top narcotics prosecutor. North Korea is barred by U.N. sanctions from importing sophisticated weapons or missiles.

Panamanian President Ricardo Martinelli said Tuesday that the ship identified as the 14,000-ton Chong Chon Gang, which had departed Cuba en route to North Korea, was carrying missiles and other arms “hidden in containers underneath the cargo of sugar.”

Martinelli tweeted a photo showing a green tube that appears to be a horizontal antenna for the SNR-75 “Fan Song” radar, which is used to guide missiles fired by the SA-2 airdefense system found in former Warsaw Pact and Soviet-allied nations, said Neil Ashdown, an analyst for IHS Jane’s Intelligence.

“It is possible that this could be being sent to North Korea to update its high-altitude airdefense capabilities,” Ashdown said. Jane’s also said the equipment could be headed to North Korea to be upgraded.

North Korea has not commented on the seizure, during which 35 North Koreans were arrested after resisting police efforts to intercept the ship in Panamanian waters last week, according to Martinelli. He said the captain had a heart attack and also tried to commit suicide.

But Cuba’s Foreign Ministry released a statement late Tuesday acknowledging that the military equipment belonged to the Caribbean nation, saying it had been shipped out to be repaired and returned to the island.

“The agreements subscribed by Cuba in this field are supported by the need to maintain our defensive capacity in order to preserve national sovereignty,” the statement read.

It said the vessel was bound for North Korea mostly loaded with sugar — 10,000 tons of it — but added that the cargo also included 240 metric tons of “obsolete defensive weapons”: two Volga and Pechora anti-aircraft missile systems, nine missiles “in parts and spares,” two Mig-21 Bis and 15 engines for those airplanes.

It concluded by saying that Havana remains “unwavering” in its commitment to international law, peace and nuclear disarmament.

The U.N. Security Council has imposed four rounds of increasingly tougher sanctions against North Korea since its first nuclear test on Oct. 9, 2006.