Iran has built a third subterranean facility to develop ballistic missiles, the semi-official Fars news agency reported on Thursday.

Fars quoted General Amir Ali Hjizadeh, the head of the Revolutionary Guards airspace division, as saying Iran would "continue to develop our missile capabilities forcefully."

"We are going to develop our ballistic power. It's normal that our enemies, that is to say, the United States and Israel, are angry when we show off our underground missile bases because they want the Iranian people to be in a position of weakness," he added.

The announcement is likely to increase tensions with the United States, with US President Donald Trump, on his maiden foreign tour, calling Iran a sponsor of militant groups and a threat to countries across the Middle East. Since taking office in January, Trump has imposed new sanctions on Iran in response to its recent missile launches, and his administration put the country "on notice."

Trump has also criticized as too soft a landmark 2015 deal with Tehran that saw the Islamic Republic scale back its nuclear program in return for the lifting of sanctions. However, the country still remains subject to a UN arms embargo and other restrictions.

Read: Trump's policy of isolation against Iran

Controversial program

The US said that Iran's missile program violates international law because the missiles could carry nuclear warheads in the future. Tehran denies that it is trying to build up a nuclear arsenal and maintains that its missile construction and launches are legitimate parts of its defense capabilities.

Iran has developed some ballistic missiles that could reach both Israeli and US bases in the region.

Thursday's report did not say where exactly the third underground facility for ballistic missiles was located in Iran, or how many missiles it had already produced.

tj/sms (Reuters, AP, AFP)