UNITED NATIONS (Reuters) - A robust monitoring regime is urgently needed in Yemen’s port city of Hodeidah to oversee compliance by the warring parties with an agreed ceasefire in the region, United Nations Yemen envoy Martin Griffiths told the Security Council on Friday.

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The Iranian-aligned Houthis and the Saudi-backed Yemen government of President Abd-Rabbu Mansour Hadi agreed on Thursday to stop fighting for Houthi-held Hodeidah and withdraw their troops, the first significant breakthrough for U.N.-led peace efforts in five years of conflict.

“A robust and competent monitoring regime is not just essential, it is also urgently needed and both parties have told us they would very much welcome it and indeed depend on it,” Griffiths told the 15-member council, adding that U.N. officials were already planning for such a deployment.

Such a monitoring mission needs the backing of the Security Council in a resolution, diplomats said.

Griffiths said retired Dutch Major General Patrick Cammaert had agreed to lead the monitoring component of the agreement, which took effect on Thursday when the deal was published. He said Cammaert could arrive in the region within days.

“Being present in the field soon is an essential part of the confidence that needs to go with the implementation of this agreement,” Griffiths said.

The council was already discussing a British-drafted resolution to enshrine five requests made by U.N. aid chief Mark Lowcock - one of which was for a truce around facilities needed for aid and commercial imports - and diplomats said that would now be reworked to endorse the agreement reached in Sweden.

“We hope to be able to work expeditiously with colleagues to bring about a Security Council resolution which will give the firmest possible support to what has been achieved so far,” British U.N. Ambassador Karen Pierce told the council.

“As requested we will of course want - with colleagues - to address the monitoring requirements,” she said.

The conflict has pushed Yemen, the poorest country on the Arabian Peninsula, to the verge of famine, and millions of people rely on food aid. More than 80 percent of Yemen’s imports used to come through Hodeidah port, but that has slowed to a trickle.

“The U.N. will take on a leading role in supporting Yemen Red Sea Ports Corporation in management and inspections at Hodeidah, Salif and Ras Issa,” Griffiths said. “The U.N. ... has developed a plan seeking specific support from member states in the port.”

U.S. Ambassador to the United Nations Nikki Haley warned that the Security Council would be watching: “We must be ready to act if one or more of the parties fails to follow through.”