Secretary-General Antonio Guterres is strongly urging all countries to implement a U.N. arms embargo against Libya, saying illegal weapons transfers are fueling fighting in the oil-rich country.

Guterres made the appeal in a report circulated Monday ahead of the U.N. Security Council's unanimous approval of a resolution authorizing the inspection of vessels on the high seas headed to or from Libya. It's extended for another year to enforce the arms embargo.

The European Union's Operation Sophia has been the only regional naval operation carrying out inspections. While the EU in March extended its mandate until Sept. 30, it suspended deployment of ships, saying instead that it would deploy more planes to monitor the area.

Guterres said immediately implementing all arms embargo measures is key to de-escalating the current Libyan situation.