Reuters- Iran has built a third underground ballistic missile production factory and will keep developing its missile program, the semi-official Fars news agency reported on Thursday, in a development likely to fuel tension with Arab neighbors and Washington.

"Iran's third underground factory has been built by the Guards in recent years ... We will continue to further develop our missile capabilities forcefully," Fars quoted the head of the Republican Guard’s airspace division, Amirali Hajizadeh, as saying.

Since taking office in January, U.S. President Donald Trump has imposed new sanctions on Iran in response to Tehran's recent missile launches, putting Tehran "on notice".

Iran's Sunni Persian Gulf neighbors and its arch-enemy Israel have expressed concerns over Tehran's ballistic missile program, seeing it as a threat to regional security.

"It is natural that our enemies America and the Zionist regime (Israel) are angry with our missile program because they want Iran to be in a weak position," Hajizadeh said.

In retaliation for the new U.S. sanctions, Iran had added nine American individuals and companies to its own list of 15 U.S. companies for alleged human rights violations and cooperation with Israel.

(Writing by Parisa Hafezi; Editing by Mark Trevelyan)