Iran said on December 5 that a letter from three European powers to the UN Security Council accusing Tehran of having nuclear-capable ballistic missiles showed their "miserable incompetence" in meeting their nuclear deal commitments.

"Latest E3 letter to UNSG on missiles is a desperate falsehood to cover up their miserable incompetence in fulfilling bare minimum of their own #JCPOA obligations," Foreign Minister Mohammad Javad Zarif tweeted, referring to the deal by its formal acronym. He urged the UK, France and Germany not to bow to "U.S. bullying".

The UK, German and French ambassadors, in a letter circulated on December 4, called on UN Secretary-General Antonio Guterres to inform the Security Council in his next report that Iran's missile programme was "inconsistent" with a UN resolution that had endorsed the nuclear deal reached between Iran and six world powers, Reuters reported.

The letter surfaced at a time of heightened friction between Iran and the West, with Tehran rolling back its commitments under the 2015 deal step by step. The strategy has been adopted to try and force the UK, France and Germany to offer meaningful protection to Iranian trade in the face of the heavy sanctions brought in by Washington last year after it unilaterally pulled out from the pact.

The US and its Arab allies want to see the nuclear deal toughened up to place restrictions on Tehran's ballistic missile programme and block backing provided by Tehran to various militias across the Middle East. Tehran says its missile development activity is solely defensive in nature.

The present nuclear deal is focused on suspending international sanctions that were levied against Iran in return for compliance with measures barring any possible path the Iranians could take to developing a nuclear weapon. Iran was in full compliance with the deal when the US walked out of it, the UN says.