DUBAI (Reuters) - Iran on Monday said new U.S. curbs on the Islamic Republic’s ballistic missile program were illegitimate, vowing to continue developing its conventional military deterrent.

The United States imposed sanctions on 11 companies and individuals on Sunday for supplying Iran’s ballistic missile program in a move delayed by over two weeks so as not to endanger this weekend’s release of U.S. prisoners.

The new measures also came after the lifting of far more comprehensive nuclear sanctions.

“The Islamic Republic will respond to these aggravating and propagandistic measures by pursuing its legal missile program stronger than before and developing its defensive capabilities,” a foreign ministry statement said.

Iran conducted a ballistic missile test in October, which the United Nations called a breach of a resolution prohibiting the Islamic Republic from developing missiles capable of delivering nuclear warheads. Iran insists the missile was designed to carry a conventional payload.

Foreign ministry spokesman Hossein Jaberi Ansari said Washington’s sales of weaponry to allies in the Middle East, worth tens of billions of dollars each year, was used to commit “war crimes against Palestinian, Lebanese and most recently Yemeni citizens”.

“The U.S. sanctions against Iran’s ballistic missile program ... have no legal or moral legitimacy,” he said.

Hardline newspapers Kayhan and Vatan-e-Emrooz splashed the news on their front pages, crowding out a triumphal speech by President Hassan Rouhani, who on Sunday hailed the lifting of the nuclear sanctions.

“Sanctions are back!” ran the Kayhan headline. The article pointed out that Tehran’s top authority, Supreme Leader Ayatollah Ali Khamenei, had said new sanctions under any pretext would constitute a breach of the nuclear deal.