The UN special envoy for Yemen said on Tuesday he is trying to renew the truce that expired last month and get warring parties to initiate talks on a path towards a settlement of the eight-year conflict.
Hans Grundberg told the UN Security Council that he detailed options to the internationally recognised government and Iran-backed Houthi rebels, and has been in constant contact on the issues that prevented an extension of the truce.
“And these discussions are making progress and they are ongoing,” Mr Grundberg said later.
He would not give details of the obstacles, stressing the need for discreet diplomacy.
“We are seeing challenges in how to frame issues related to the economic matters such as the payment of salaries, and also broader issues which have an implication on the more long-term settlement of the conflict,” Mr Grundberg said.
The UN-backed truce took effect in April and raised hopes for a longer pause in fighting than six months.
Yemen's devastating conflict began in 2014, when the Iranian-backed Houthis seized the capital Sanaa and much of northern Yemen.
A Saudi-led coalition intervened in 2015 at the request of the government.
Mr Grundberg told the council that in the seven weeks since the truce expired, “despite incidents of concern, we have fortunately not seen a return to full-fledged war".
But in recent weeks, he said the Houthis have attacked oil terminals and ports “with the aim of depriving the government of Yemen of its main source of revenue from exporting oil".
Mr Grundberg said these attacks “have significant economic repercussions", undermine the welfare of the Yemeni people and “risk setting off a spiral of military and economic escalation, a pattern we have seen play out before over the course of Yemen’s war".
While overall violence has only increased slightly since the six months of truce, he said there “a concerning uptick in incidents” with civilian casualties in Marib, which the Houthis have long tried to seize, and in Yemen's third-largest city, Taiz.
These attacks “demonstrate how fragile the situation remains and underscores, once more, the need for the parties to urgently reach an agreement to renew the truce", Mr Grundberg said.
Reena Ghelani, the operations director in the UN humanitarian office, told the council that this month four displaced civilians were killed and at least five injured when a weapons storage facility exploded in Marib due to fighting.
And Ms Ghelani said that in the last week of October, shelling and sniper fire killed two civilians and injured eight others, many of them children, in Taiz.
She said landmines and unexploded ordnance continue to account for the largest number of civilian casualties, killing and injuring more than 164 people, including 74 children, between July and September.
Ms Ghelani said threats to civilians extended beyond the immediate effects of the war.
“Hunger continues to haunt more than half the population in Yemen, preying on the most vulnerable,” she said.
“Seventeen million people still do not know where they will get their next meal.”
The delivery of aid has also been hampered over recent months, Ms Ghelani said, because the Houthis imposed restrictions especially affecting female staff and beneficiaries, “leaving us less room to operate".
She said migrants and refugees also faced dangers, with more than 50,000 migrants taking the perilous sea journey from the Horn of Africa to Yemen so far this year in search of a better life.
Ms Ghelani said some never made it because of their flimsy and overcrowded vessels including, a raft that sank last month leaving three people dead and 28 missing.