The United Nations envoy to Yemen will visit the rebel-held battleground port city of Hodeida this week, a UN source said Thursday, as he presses warring parties to uphold pledges to join peace talks.

Martin Griffiths, who arrived in the rebel-held capital Sanaa on Wednesday, was in the Arabian Peninsula country to lay the groundwork for next month’s negotiations in Sweden.

The British diplomat’s visit to Hodeida on Friday was aimed at encouraging Iran-aligned Huthi rebels and government forces backed by a Saudi-led coalition to stay calm ahead of the talks in Stockholm, the UN source said.

The conflict in Yemen, which escalated when the Saudi-led alliance intervened in 2015, has killed thousands and sparked what the United Nations has called the world’s worst humanitarian crisis.

UN agencies say up to 14 million Yemenis would be at risk of starvation if fighting closes the port of Hodeida, through which nearly all of the country’s imports and humanitarian aid pass.

Both sides have in the past week expressed support for the envoy and his mission to hold discussions, but military officials have said that intermittent clashes continued to erupt in the Red Sea city of Hodeida.

Mohammed Ali al-Huthi, head of the rebels’ Higher Revolutionary Committee and an influential political figure, said the rebels were ready for peace. “We support peace.

We are ready for peace if that is what they want,” he told reporters after meeting Griffiths on Thursday. “I do not think anyone can doubt our desire for peace,” he said, adding the envoy would hold talks with rebel chief Abdulmalik al-Huthi before heading to Hodeida.

United States Defence Secretary Jim Mattis confirmed on Wednesday peace discussions between the Huthis and the internationally-recognised government would take place early December.

He said Saudi Arabia and United Arab Emirates which is also a key member of the military coalition supporting the loyalists were “fully on board”.

“It looks like that very, very early in December, up in Sweden, we’ll see both the Huthi rebel side and the UN-recognised government, President Abedrabbo Mansour Hadi’s government, will be up there.”

Mattis last month made a surprise call for a ceasefire in Yemen and urged warring parties to enter negotiations within the next 30 days. The UN has now pushed that deadline back to the end of the year.

Mattis’ latest comments came as the US State Department said talks must not be delayed any longer.

The United States has been providing bombs and other weapons, as well as intelligence support, to the Saudi-led coalition backing Hadi, but recently ended its refuelling support for Saudi warplanes.

On Monday, Britain presented to the UN Security Council a draft resolution urging an immediate truce in Hodeida.

The draft, circulated by Britain to the 14 other council members, and seen by AFP, sets a two-week deadline for the warring sides to remove all barriers to humanitarian aid.