By Michelle Nichols

UNITED NATIONS (Reuters) - The United Nations chief expressed concern to the Security Council that Iran may have violated an arms embargo by supplying weapons and missiles to Lebanese Shi'ite group Hezbollah, according to a confidential report, seen by Reuters on Sunday.

The second bi-annual report, due to be discussed by the 15-member council on Jan. 18, also cites an accusation by France that an arms shipment seized in the northern Indian Ocean in March was from Iran and likely bound for Somalia or Yemen.

Most U.N. sanctions were lifted a year ago under a deal Iran made with Britain, France, Germany, China, Russia, the United States and the European Union to curb its nuclear program. But Iran is still subject to an arms embargo and other restrictions, which are not technically part of the nuclear agreement.

The report was submitted to the Security Council on Dec. 30 by U.N. Secretary-General Ban Ki-moon before he was succeeded by Antonio Guterres on Jan. 1. It comes just weeks before U.S. President-elect Donald Trump, who has threatened to either scrap the nuclear agreement or seek a better deal, takes office.

"In a televised speech broadcast by Al Manar TV on 24 June 2016, Hassan Nasrallah, the Secretary-General of Hezbollah, stated that the budget of Hezbollah, its salaries, expenses, weapons and missiles all came from the Islamic Republic of Iran," Ban wrote in the report.

"I am very concerned by this statement, which suggests that transfers of arms and related materiel from the Islamic Republic of Iran to Hezbollah may have been undertaken contrary (to a Security Council resolution)," Ban said.

When asked by the United Nations to clarify the issue, Iran's mission to the United Nations said "measures undertaken by the Islamic Republic of Iran in combating terrorism and violent extremism in the region have been consistent with its national security interests and international commitments."

Under a Security Council resolution enshrining the deal, which came into effect a year ago, the U.N. secretary-general is required to report every six months to the council on any violations of sanctions still in place.

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"Since 16 January 2016, I have not received any report on the supply, sale, transfer or export to the Islamic Republic of Iran of nuclear-related items undertaken contrary to the (resolution)," Ban wrote.

In Ban's first report in July he said ballistic missile launches carried out by Iran in March were "not consistent with the constructive spirit" of a nuclear deal, but it is up to the council to decide if they violated the resolution.

In the most recent report, he wrote that since July "no information regarding Iranian ballistic missile activity or ballistic missile-related transfers ... were brought to my attention or that of the Security Council."

(Reporting by Michelle Nichols; Editing by Alan Crosby)