DUBAI - Iran displayed what it described as a domestically built long-range, surface-to-air missile air defence system on Thursday, at a time of rising tension with the United States.

Iran shot down a U.S. military surveillance drone in the Gulf with a surface-to-air missile in June. It says the drone was over its territory, but the United States says it was in international airspace.

State television showed President Hassan Rouhani attending an unveiling ceremony for the mobile Bavar-373 system, which Iranian media have described as a competitor to the Russian S-300 missile system.

"With this long-range air defence system, we can detect ... targets or planes at more than 300 km (190 miles), lock it at about 250 km, and destroy it at 200 km," Defence Minister Amir Hatami told state television.

The system's unveiling came on Iran's National Defence Industry Day. Iran has developed a large domestic arms industry in the face of international sanctions and embargoes that have barred it from importing many weapons.

Western military analysts say Iran often exaggerates its weapons capabilities, though concerns about its long-range ballistic missile programme contributed to Washington last year leaving the pact that Iran sealed with world powers in 2015 to rein in its nuclear ambitions in exchange for an easing of economic sanctions.

On Tuesday, U.S. Secretary of State Mike Pompeo warned at a U.N. Security Council meeting that, under the Iran nuclear deal, a United Nations arms embargo on Iran was due to expire in October 2020.

(Reporting by Dubai newsroom Editing by Paul Tait) ((dubai.newsroom@thomsonreuters.com;))