UNITED NATIONS -- The United Nations has determined that debris from five ballistic missiles launched from Yemen into Saudi Arabia since July 2017 contained components manufactured in Iran and shared key design features with an Iranian missile, Secretary-General Antonio Guterres said in a new report.

But the UN chief said in the report to the Security Council obtained Thursday by The Associated Press that the United Nations has been unable to determine whether the missile parts and technology were transferred from Iran after Jan. 16, 2016, when UN restrictions came into force.

Guterres said the UN is also "confident" that some arms seized by Bahrain and recovered by the United Arab Emirates from an unmanned vessel laden with explosives were manufactured in Iran. But he said it found "no indications" of whether the items were transferred from Iran after UN restrictions took effect.

The secretary-general was reporting on implementation of a 2015 Security Council resolution that endorsed the Iran nuclear deal. The resolution includes restrictions that took effect on Jan. 16, 2016, on transfers to or from Iran of nuclear and ballistic missile material as well as arms.

Guterres stressed that the International Atomic Energy Agency has reported to the council 11 times that Iran is implementing its nuclear-related commitments. He expressed deep regret that the United States announced its withdrawal from the agreement, which he called "a major achievement in nuclear non-proliferation, which has contributed to regional and international peace and security."

In other key findings, the secretary-general said the UN is looking into reports from two unnamed countries that Iran received "dual-use items, materials, equipment, goods and technology" in violation of UN restrictions.

Guterres also said the UN hasn’t had an opportunity to examine a drone that Israel intercepted and downed after it entered its airspace. Israel said it was Iranian.

The secretary-general noted that Iranian media had reported that "various Iranian unmanned aerial vehicles" have been deployed in Syria, adding that the UN "has no information regarding the owner or operator" of the drone.

Guterres reported that on May 21, the Hamas leader in Gaza, Yahya Sinwar, said in a television interview that Iran provided the Al-Qassam Brigades and other armed groups in the territory with "money, (military) equipment and expertise."

Guterres said any Iranian arms transfers after Jan. 16, 2016, would violate the UN restrictions.

He also reported receiving a letter dated May 15 from Ukraine’s UN ambassador indicating that its security service "prevented an attempt by two Iranian nationals to procure and transfer" to Iran components of a Kh-31 air-to-surface missile and related technical documents.

Guterres said Ukraine stated that the missile type hadn’t been used in the country since 1991 and all remaining components were properly stored by its armed forces.