Britain, France, Germany and the US have asked a UN Security Council sanctions committee to investigate Iran's recent missile test, branding it a serious violation of UN resolutions.
US ambassador Samantha Power told the council on Wednesday (local time) that the medium-range ballistic missile launched on October 10 was capable of delivering a nuclear weapon.
The four countries presented a report to the sanctions committee making the case that the missile test was a "serious violation" and requesting "appropriate action", according to a joint letter obtained by AFP.
Power called it a "provocative launch" and said the "United States considers it to be a serious matter" that undermines regional stability.
The request to the committee marks a first step toward possible sanctions, although such a decision would require agreement from China and Russia.
The four countries took part along with China and Russia in successful negotiations to reach a historic deal with Iran in July that calls for lifting sanctions in exchange for curbs on Tehran's nuclear program.
British Ambassador Matthew Rycroft told reporters that there was no deadline for the committee to report back to the 15-member Security Council on its findings, but that there was a "clear sense of urgency".
The four countries maintain that the missile test violates Security Council resolution 1929, which was adopted in 2010.
That resolution prohibits Tehran from conducting launches of ballistic missiles capable of delivering nuclear weapons.
Iran on Saturday denied that the missile launch was in violation of UN resolutions, with Foreign Minister Mohammad Javad Zarif saying that it was not designed to carry nuclear warheads.
Iran insists it has no plans to develop atomic weapons.