A U.S. Navy plane apparently accidentally crossed into Venezuela's airspace Saturday night, triggering protests from that country, according to a U.S. defense official familiar with the report.

The S-3 Viking aircraft, based in Curacao, was on a training mission in international airspace near Los Roques Island, Venezuela, and experienced "intermittent navigational problems," said the official, who spoke on condition of anonymity because of the sensitivity of the issue.

The aircraft is used for counter-narcotics missions. Navy crew on the S-3 reported they had a brief radio conversation with air traffic control personnel in Maiquetia, and believed that they had mistakenly flown into Venezuelan airspace, the official said.

Navy officials are investigating the incident to determine exactly what happened.

According to the defense official, the S-3 crew was under the air control of Curacao, but was told to switch frequencies to Maiquetia. Based on the "agitated" tone of the conversation with traffic controllers in Maiquetia, the official said the crew realized the likely error.

The official said the crew had some language problems during the three-minute radio conversation with Maiquetia personnel.

"They promptly responded and identified themselves as U.S. Navy, on a training mission in international airspace, and that a navigational error had possibly occurred," said the official.

The S-3 aircraft were originally used for anti-submarine warfare and maritime surveillance, but are now used largely for counter-narcotics activities. The S-3 involved in the incident provides support for the Joint Interagency Task Force South, based in Key West, Fla.

Venezuela will summon the U.S. ambassador to explain the violation of its airspace by a U.S. military plane, the country's foreign minister said Monday.

Foreign Minister Nicolas Maduro said U.S. Ambassador Patrick Duddy will be called in to discuss the matter. "We will ask for an explanation," Maduro said.