Kenyan security forces discovered a cache of undeclared weapons on a Norwegian ship carrying a consignment of United Nations vehicles, authorities said Wednesday.

Rifles and Russian rocket-propelled grenade launchers were among the "cache of firearms" discovered on the vessel, Mombasa police chief Francis Wanjohi told reporters, according to the Associated Press.

Twenty of the crew members are set to be charged with illegal weapons trafficking, and Kenyan authorities are trying to determine if the weapons were being transported by a U.N. agency, and why the arms were not declared in the ship’s manifest.

"None of these were declared in the manifest, therefore the Kenyan government was not aware of that,” Wanjohi said. "It is procedural that everything must be declared, but in this case the Kenyan government was not made aware."

The company that operated the vessel, Höegh Autoliners, also confirmed the presence of the weapons and said that they had been loaded without the shipping company’s knowledge. “It is our understanding that these weapons belong to the U.N. vehicles in which they were found, and were for use by the U.N. during their peacekeeping mission,” the company said in a statement.

“The weapons were not declared to us at the time the cargo was loaded, and the fact that weapons were in the vehicles is in violation with our terms of transportation, which clearly states that no arms or ammunition are accepted for shipment.”

Local media reports also alleged that drugs in a crystal form were found during the search, but these were not officially verified. “We have noted reports in the press that in addition to weapons, the Kenyan authorities have found a substance which is being tested to ascertain whether could be drugs. We have no clear information at this point as to whether this is correct or not,” Höegh said.

A U.N. spokesman said that the weapons were part of a declared cargo packed in India that was set to be used by the Indian battalion of the U.N. peacekeeping mission in Congo.

“The weapons were declared in the bill of lading but not in the manifest," the unnamed spokesman said. "A request was sent by the U.N. contractor responsible for the shipment to the Mombasa ship agent to amend the manifest, but since this was not possible, a declaration of the weapons accompanying the military vehicles was attached.

"It is unfortunate that the Kenyan authorities inspected the cargo without a U.N. presence, which runs contrary to established protocol," the spokesman said, adding that it is standard practice for weapons to be dismantled and packed inside during shipping to avoid damage.