The attacks come amid a simmering standoff between the United States and Iran (File Photo)

Iran shot down a U.S. naval surveillance drone near the Strait of Hormuz, Iranian and U.S. officials said Thursday, adding to weeks of tensions in the Persian Gulf region amid growing concerns of a wider military confrontation.

Iran's Revolutionary Guard Corps said in a statement that it targeted the drone - which it identified as an RQ-4 Global Hawk - inside Iranian airspace over the southern province of Hormozgan, next to the strategic Strait of Hormuz.

The U.S. Central Command confirmed the incident Thursday but denied the aircraft was in Iranian airspace.

"U.S. Central Command can confirm that a U.S. Navy . . . aircraft was shot down by an Iranian surface-to-air missile system while operating in international airspace over the Strait of Hormuz," a Centcom spokesman, Capt. Bill Urban, said in a statement.

He said the drone, a RQ-4A Global Hawk, was shot down in the early hours of the morning Wednesday.

"Iranian reports that the aircraft was over Iran are false," he said. "This was an unprovoked attack on a U.S. surveillance asset in international airspace."

The Revolutionary Guard's chief commander, Maj. Gen. Hossein Salami, called the downing of the drone "a clear message to America."

A U.S. official confirmed the episode to the Associated Press and said the drone was targeted by an Iranian surface-to-air missile in international airspace over the Strait of Hormuz. Nearly a quarter of the world's oil passes through the waterway, which connects Middle East energy producers to markets around the globe.

"Our borders are Iran's red line, and we will react strongly against any aggression," Salami said Thursday in remarks carried by Iranian state television.

"Iran is not seeking war with any country, but we are fully prepared to defend Iran," he said.

Iran's Mashregh news agency, which is close to the Revolutionary Guard, reported that the drone was shot down by the Guards' Sevom Khordad missile defense system.

The Guard said in an updated statement that the U.S. drone had "left a base in the southern Persian Gulf" and was heading toward Iran's Chabahar port "in full secrecy, violating the rules of international aviation."

"We warn of the consequences of such illegal and provocative measures," Iranian Foreign Ministry spokesman Abbas Mousavi said, state TV reported.

The attacks come amid a simmering standoff between the United States and Iran in the Persian Gulf region following assaults on Japanese and Norwegian tankers near the Strait of Hormuz. The Trump administration has blamed Iran for the attacks, at least one of which was carried out using a limpet mine similar to those previously displayed at Iranian military parades.

Iran has denied involvement and called the accusation "unfair" and "a lie."

The U.S. Central Command said that a modified Iranian SA-7 surface-to-air missile was fired at an MQ-9 reaper drone over the Gulf of Oman as it surveilled the attack on the Japanese tanker, Kokuka Courageous, on June 13.

Earlier this month, Houthi rebels shot down an MQ-9 over Yemen using an SA-6 surface-to-air missile, Centcom said, which it claimed "was enabled by Iranian assistance."

Saudi Arabia said Thursday that Yemen's Houthi rebels fired a rocket targeting a desalination plant in the kingdom overnight. The rocket caused no damage, the official Saudi Press Agency reported, quoting military spokesman Col. Turki al-Maliki.

In December 2011, Iran captured an American stealth drone operated from a base in Afghanistan, purportedly after an Iranian cyberwarfare unit commandeered it and landed it near the city of Kashmar in northeastern Iran. Tehran claimed that the Lockheed Martin RQ-170 Sentinel surveillance drone was detected inside Iranian airspace about 140 miles from the border with Afghanistan. U.S. officials said operators lost control of the drone while it was flying on the Afghan side of the border with Iran.

Iran later claimed that it recovered data from the drone and reverse-engineered the aircraft to produce its own version.