BUENOS AIRES, Argentina - Argentina is accusing the US military of trying to sneak guns and spy equipment into the country under the guise of providing a routine police training course _ a charge disputed Monday by US officials.

Argentine authorities say they seized nearly 1,000 cubic feet of undeclared equipment, describing it as machine guns and ammunition, drugs and spy equipment. It was on a US Air Force C-17 cargo plane that landed Thursday with material for a training course that a US Special Forces team had been invited to provide to Argentina's federal police.

"Argentine law must be complied with by all, without exception," Foreign Minister Hector Timerman told Arturo Valenzuela, the assistant US secretary of state for Western Hemisphere affairs, when Valenzuela called him to complain about how authorities handled the cargo, the ministry said.

Timerman also said Argentina would file an official protest in Washington and ask for a shared investigation into why the US Air Force would try to violate Argentine law, the ministry said.

The seized material includes equipment "for intercepting communications, various sophisticated and powerful GPS devices, technological elements containing codes labeled secret, and a trunk full of expired medicine," the ministry said.

An Argentine federal judge is demanding a full accounting from the foreign ministry, and some lawmakers vowed to hold investigative hearings.

State Department spokesman P.J. Crowley said he could not confirm if a protest had been filed, but he called on Argentina to return the US equipment.

"We are puzzled and disturbed by the actions of Argentine officials," he told reporters in Washington.

Crowley called the search of the plane "unusual and unannounced" and said minor discrepancies in the manifest "were the kind of thing that could have been cleared up on the ground by customs officials."

The plane arrived at a sensitive time for Argentine-US relations. Since the White House announced that President Barack Obama would visit Chile and Brazil but skip Argentina in his first trip to South America, Timerman has complained about US military policies _ in particular, training that the US provides to Latin American police and military at the International Law Enforcement Academy in El Salvador.

The academy replaced the US military's School of the Americas, where critics contend many Latin American military figures learned torture techniques that served the region's dictatorships in decades past. Human rights is a main thrust of the academy's curriculum, but Timerman has focused on the darker history.

A US State Department official with knowledge of the events told The Associated Press that all the key material in the shipment was properly declared and authorized by Argentina, describing the undeclared equipment as a minor problem with the plane's manifest that could have been resolved privately.

For example, the official said, each machine gun and related equipment was declared. But extra gun barrels brought to replace barrels that overheat during live-fire exercises were seized because they lacked matching serial numbers, the official said.

The official agreed to discuss the matter only if not quoted by name because of the sensitivity of continuing talks over the issue.

Also seized was a US medic's kit, brought along in case anyone got injured. While the kit was declared, all the drugs inside weren't individually listed, the official said.

The purported spy equipment is simply satellite phones, which the nine-member Special Forces training team carries with them in the field in case they must communicate through secure channels to their US commanders, the official said. Only one of the three phones listed in the manifest was declared, and the inventory didn't specify all the related computer equipment or classified codes used to make the calls. All were seized, the official said.

"This elite team from the US is on active duty. They're on call. They absolutely had to have it because at any moment if there was a hostage crisis that broke out in the world, they would have to leave and use it to communicate," the official said.

Stretchers, bandages and military rations make up most of the rest of the undeclared equipment. Argentine officials told the Americans during planning for the training course not to worry about declaring such material, the official said.

The course was canceled and the C-17 flew home with the Special Forces team, the official said.

Associated Press writer Matthew Lee in Washington contributed to this report.