UPDATE 1-Iran tells U.N. it reserves right to self-defense over Soleimani killing

(Adds Guterres spokesman’s statement, background, byline, previous dateline WASHINGTON)

UNITED NATIONS, Jan 3 (Reuters) - Iran told the U.N. Security Council and Secretary-General Antonio Guterres on Friday it reserves the right to self-defense under international law after the United States killed its most prominent military commander Qassem Soleimani.

In a letter, Iranian U.N. Ambassador Majid Takht Ravanchi said the killing of Soleimani “is an obvious example of State terrorism and, as a criminal act, constitutes a gross violation of the fundamental principles of international law, including, in particular ... the Charter of the United Nations.”

Soleimani, a 62-year-old general who headed the overseas arm of Iran’s Revolutionary Guards, was regarded as the country’s second most powerful figure after Supreme Leader Ayatollah Ali Khamenei.

The United States killed Soleimani in an overnight attack in Iraq authorized by U.S. President Donald Trump. A senior Trump administration official said Soleimani had been planning imminent attacks on U.S. personnel in the Middle East.

The United States could seek to justify killing Soleimani under Article 51 of the U.N. Charter, which covers an individual or collective right to self-defense against armed attack.

Under Article 51, countries are required to “immediately report” to the 15-member Security Council any measures taken in exercising the right of self-defense. The United States used Article 51 to justify taking action in Syria against Islamic State militants in 2014.

Diplomats said no such letter had yet been received from Washington on the killing of Soleimani.

Guterres is deeply concerned by the recent rise in tensions in the Middle East, his spokesman, Farhan Haq, said in a statement earlier on Friday.

“This is a moment in which leaders must exercise maximum restraint. The world cannot afford another war in the Gulf,” Haq said.

Reporting by Michelle Nichols; Editing by Mohammad Zargham and Richard Chang