UN Yemen envoy Martin Griffiths said on Thursday at the UN Security Countil that any escalation of violence in Yemen could not be reduced without a political process, but thanked parties — including the Kingdom of Saudi Arabia — for their work toward that goal.

Griffiths made his briefing at the Security Council session after holding several consultations in the Middle East and meetings with various US officials in Washington.

It is the first session on Yemen in 2020.

Before his briefing on Thursday, Griffiths met with US Secretary of Defense Mark Esper on Wednesday.

Griffiths' address came as separatists and forces loyal to the internationally-recognized government who started clashing last summer began pulling back from a key southern city, something confirmed by military officials on Thursday.

The pullout, envisaged under the Saudi-brokered Riyadh Agreement peace deal, began this week, the Yemeni officials told AP. They spoke on condition of anonymity in line with regulations.

The infighting that broke out in August between the secessionists and troops loyal to Yemeni President Abed Rabbo Mansour Hadi threatened their alliance in the Arab coalition that has been fighting against the country's Iranian-backed Houthi militia since 2015.