The United Nations has urged Yemen’s warring factions to immediately withdraw troops from the lifeline port of Hodeidah and save a vital truce, as rights groups warned aid was not getting through to thousands who could starve to death.

The stark warning came as the UN confirmed that eight civilians had been killed and 30 wounded when a camp for displaced people in the northwestern province of Hajjah was shelled this week.

The UN had hoped that a ceasefire would hold and humanitarian aid would flow after both the Houthi rebel group and the recognised Yemeni government agreed to leave Hodeidah, Yemen’s main entry point for food and medical supplies.

According to the deal hammered out in December talks in Sweden, a local administration was supposed to take control of the Red Sea city and be monitored by a special UN mission.

But UN envoy Martin Griffiths, who arrived in the rebel-held capital on Monday, acknowledged the proposed timelines for a pull-out from the port had passed unheeded while the country stood on the brink of famine.

“The initial timelines were rather ambitious,” he said on Twitter. “We are dealing with a complex situation on the ground.”

Lise Grande, the UN humanitarian coordinator for Yemen, meanwhile called the shelling of a Hajjah displacement a “senseless attack”.

“The people who have fled their homes ... have lost so much already. An attack like this cannot be justified – ever,” she said. No one has claimed responsibility for the killing.

War erupted in Yemen in 2014 when the Iran-backed Houthi rebels swept control of the country forcing recognised President Abedrabbo Mansour Hadi to flee.

Saudi Arabia and its Gulf allies, fearing Iran’s influence on their borders, launched a bombing campaign to reinstate their ally Mr Hadi.

Four years on the conflict shows little sign of ending and has sparked the world’s worst humanitarian crisis. It has also pushed the country to the brink of famine.

The UN has warned that as many as 13 million people could starve to death if aid is not able to reach the worst hit areas.

Food aid for Yemenis stolen Show all 21 1 /21 Food aid for Yemenis stolen Food aid for Yemenis stolen People walk in a shelter for displaced persons in Ibb, Yemen, in this 3 Aug 2018 photo. (AP Photo/Nariman El-Mofty) Food aid for Yemenis stolen People stand near their rooms inside a shelter for displaced persons in Ibb, Yemen, in this 3 Aug 2018 photo. (AP Photo/Nariman El-Mofty) Food aid for Yemenis stolen A baby sleeps inside a shelter for displaced persons in Ibb, Yemen, in this 3 Aug 2018 photo. (Photo/Nariman El-Mofty) Food aid for Yemenis stolen A woman sits with her baby inside a shelter for displaced persons in Ibb, Yemen, in this 3 Aug 2018 photo. (AP Photo/Nariman El-Mofty) Food aid for Yemenis stolen Sisters play in their room at a shelter for displaced persons in Ibb, Yemen in this 3 Aug 2018 photo. (AP Photo/Nariman El-Mofty) Food aid for Yemenis stolen The entrance of the hangar of the United Nations in Aden, Yemen, in this 23 July 2018 photo. (AP Photo/Nariman El-Mofty) Food aid for Yemenis stolen A man sells aid supplies at a market in Aden, Yemen, in this 23 July 2018 photo. (AP Photo/Nariman El-Mofty) Food aid for Yemenis stolen The entrance to the port where aid is received, in Aden, Yemen, is shown in this 23 July 2018 photo. (AP Photo/Nariman El-Mofty) Food aid for Yemenis stolen This 24 July 2018 photo shows a gas station on a road in Shabwah, Yemen. (AP Photo/Nariman El-Mofty) Food aid for Yemenis stolen A worn-out list of registered names for aid by Relief International, part of the World Food Program, is posted in Aden, Yemen in this 23 July 2018 photo. (AP Photo/Nariman El-Mofty) Food aid for Yemenis stolen A truck carries aid on a road in Aden, Yemen, in this 23 July 2018 photo. (AP Photo/Nariman El-Mofty) Food aid for Yemenis stolen A man fixes his scarf at a shelter for displaced persons in Ibb, Yemen, in this 3 Aug 2018 photo. (AP Photo/Nariman El-Mofty) Food aid for Yemenis stolen Children play in a room at a shelter for displaced persons in Ibb, Yemen, in this 3 Aug 2018 photo. (AP Photo/Nariman El-Mofty) Food aid for Yemenis stolen Children look out of their room at a shelter for displaced persons in Ibb, Yemen, in this 3 Aug 2018 photo. (AP Photo/Nariman El-Mofty) Food aid for Yemenis stolen A woman holds her baby as she leaves her room in a shelter for displaced persons in Ibb, Yemen in this 3 Aug 2018 photo. (AP Photo/Nariman El-Mofty) Food aid for Yemenis stolen A family poses for a photograph in their room at a shelter for displaced persons in Ibb, Yemen, in this 3 Aug 2018 photo. (AP Photo/Nariman El-Mofty) Food aid for Yemenis stolen A family sits in their room at a shelter for displaced persons in Ibb, Yemen, in this 3 Aug 2018 photo. (AP Photo/Nariman El-Mofty) Food aid for Yemenis stolen A bucket filled with bread at a shelter for displaced persons in Ibb, Yemen, is shown in this 3 Aug 2018 photo. (AP Photo/Nariman El-Mofty) Food aid for Yemenis stolen A family poses for a photograph in a shelter for displaced persons in Ibb, Yemen, in this 3 Aug 2018 photo. (AP Photo/Nariman El-Mofty) Food aid for Yemenis stolen A child stands in a room at a shelter for displaced persons in Ibb, Yemen, in this 3 Aug 2018 photo. (AP Photo/Nariman El-Mofty) Food aid for Yemenis stolen A shelter for displaced persons in Ibb, Yemen, is shown in this 3 Aug 2018 photo. (AP Photo/Nariman El-Mofty)

Despite negotiations, the Houthi still control Hodeidah while troops loyal to the government and a Saudi-led coalition backing them are amassed on its outskirts as both sides cannot agree who should control the city or withdraw.

The target of 7 January for forces to leave has passed and skirmishes continue instead; residents and aid workers have told Reuters that barricades, trenches and roadblocks have been reinforced.

Mr Griffiths travelled to Sana’a on Monday to try to iron out the differences holding back the deal, there are also disagreements between the Houthis and retired Dutch Maj Gen Patrick Cammaert, who is heading the UN mission charged with monitoring the ceasefire.

A UN-marked armoured vehicle in Maj Gen Cammaert’s convoy was hit with a round of small-arms fire earlier this month.

The motorcade of UN special envoy for Yemen Martin Griffiths following his arrival at Sana’a International yesterday (AFP/Getty) (MOHAMMED HUWAIS/AFP/Getty Images)

Despite this, Mr Griffiths remained optimistic, telling Saudi-owned newspaper Asharq al-Awsat on Monday that “changes in timeline are expected”.

“That momentum is still there, even if we have seen the timelines for implementation extended,” he said.

However, vital humanitarian aid is not getting to those hardest hit by the fighting, a coalition of 14 aid agencies warned in a meeting in London on Monday.

Kimberley Brown of the British Red Cross said 85,000 children had lost their lives and malnutrition was taking a huge toll.

“I know from my colleagues that the situation is absolutely deteriorating at the moment,” she said.

Ahmed Murshed, 44, fled Hodeidah last June when airstrikes destroyed his cafeteria, as well as the houses belonging to his brother and brother-in-law (Islamic Relief)

Meanwhile, Yemeni families displaced from Hodeidah said their relatives who have remained in the port city still live under fire, while they struggle to survive in poorly equipped IDP camps or makeshift homes in comparatively safer areas of the country.

“My relatives in Hodeidah tell me that they live amid terror and worry and they are expecting death at any moment,” said Ahmed Murshed, 44, who fled the Red Sea coast last June for Taiz. His family were forced to sell their belongings to fund the three-day journey through the mountains to the southwestern city.

He said he now relies on food, mattresses and blankets from Islamic Relief.

My relatives in Hodeidah tell me that they live amid terror... they expect death at any moment Ahmed Murshed, 44, a Yemeni who fled Hodeidah

“I am dependent on organisations to help me eke out a living for 26 family members, some of them need medicines. There is not enough water in the house and we have to fetch it from far distances,” he added.

Abdu Muqbel, 65, and his family of seven also fled Hodeidah under fire to an IDP camp in Taiz after his wife was hit by shrapnel in her neck.

Abdu Muqbel, who was displaced from Hodeidah, says his relatives who remained in the port city fear for their lives (Islamic Relief)

He said his family barely survived in the camp for two years until Islamic Relief recently came to help.

But despite the hardships they face in Taiz, Mr Muqbel said it is not possible to go back to Hodeidah because fighting is still plaguing the city and stopping access to food.

“I heard about the ceasefire but my relatives there told me that battles have started again, and they do not dare to sleep with the buzzing of warplanes over them day and night,” he said.