By Michelle Nichols and Louis Charbonneau

UNITED NATIONS (Reuters) - The United States, Britain, France and Germany called on Wednesday for the United Nations Security Council's Iran sanctions committee to take action over a missile test by Tehran that they said violated a U.N. ban.

In a letter containing details on the launch, they said the ballistic missile was "inherently capable of delivering a nuclear weapon."

The letter, seen by Reuters, was sent to the committee after the United States raised the issue in the 15-member Security Council.

"We trust that this information will assist the Committee in its responsibility to examine and take appropriate action in response to violations of U.N. Security Council resolutions," they wrote.

Iran said earlier this month that it had tested a new precision-guided ballistic missile.

Diplomats have said it was possible for the sanctions committee to blacklist additional Iranian individuals or entities if it determined that the missile launch had breached the U.N. ban. However, they said Russia and China, which have opposed the sanctions on Iran's missile program, might block any such moves.

"The United States will continue to press the Security Council to respond effectively to any future violations ... Full and robust enforcement of all relevant U.N. measures is and will remain critical," U.S. ambassador to the United Nations Samantha Power said in a statement on Wednesday.

Iran has disputed the Western assessment that the missile was capable of delivering a nuclear warhead.

"None of the Islamic Republic of Iran's missiles has been designed for a nuclear capability," Iranian Foreign Minister Mohammad Javad Zarif said on Saturday, according to Iran's state news agency IRNA.

Ballistic missile tests by Iran are banned under a 2010 Security Council resolution that remains valid until a nuclear deal between Iran and six world powers is implemented.

Under that deal, reached on July 14, most sanctions on Iran will be lifted in exchange for curbs on its nuclear program. Once it takes effect, Iran will still be "called upon" to refrain from work on ballistic missiles designed to deliver nuclear weapons for up to eight years.

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U.S. and European officials have said it is unlikely the deal will be fully implemented before next year.

The deal allows for supply of ballistic missile technology to Tehran with Security Council approval, but the United States has pledged to veto any such requests.

The missile test is not a violation of the nuclear deal, U.S. officials have said.

Iranian Supreme Leader Ayatollah Ali Khamenei on Wednesday conditionally approved the nuclear deal but warned it would be violated if any of the six world powers imposed any sanctions on any level and under any pretext.

(Reporting by Michelle Nichols and Louis Charbonneau in New York and Sam Wilkin in Dubai; Editing by James Dalgleish, Toni Reinhold)