Iran successfully tested a precision-guided medium-range ballistic missile two weeks ago, a military official said on Monday, as Tehran continues to bolster what it insists is a purely defensive arsenal.

The Islamic Republic has worked to improve the range and accuracy of its missiles over the past year, which it says will make them a more potent deterrent with conventional warheads against its enemy Israel.

"We tested a missile with a range of 2,000 kms (1,240 miles) and eight metres error margin two weeks ago. An eight-metre error margin means ... full accuracy," the Tasnim news agency quoted Brigadier General Ali Abdollahi as saying.

The United States and some European powers have said other recent tests violate a United Nations resolution that prohibits Iran from firing any missile capable of carrying a nuclear warhead. Iran says the missiles are not designed to carry nuclear warheads, which it does not possess.

Washington has imposed new sanctions on Tehran over recent tests, even after it lifted nuclear-related sanctions in January as Tehran implemented the nuclear deal it reached with world powers last year.

Iran's top leader Ayatollah Ali Khamenei said in March that missile development was key to the Islamic Republic's future, in order to maintain its defensive power and resist threats from its enemies.