Aid agencies and medical staff on the ground in Hodeidah have begged the international community to intervene to stop the violence in the besieged Yemeni city as coalition and Houthi rebel forces struggle to gain the upper hand ahead of a planned ceasefire at the end of the month.

“The violence is unbearable, I cannot tell you. We’re surrounded by strikes from the air, sea and land,” said Wafa Abdullah Saleh, a nurse at the barely functioning al-Olafi hospital in the Houthi-controlled city centre.

“The hospital treats the hungry and people injured in airstrikes day in and day out, but there is a serious shortage of medicine,” she said. “Even if we try our hardest we cannot treat patients because we lack the necessities for basic operations.”

Hodeidah, a large and cosmopolitan city on Yemen’s Red Sea coast, was seized by Yemen’s Houthi rebels early on in the three-year-old war. More than 80% of the country’s food, aid, fuel and commercial goods enter the country through the city’s port.

Facebook Twitter Pinterest Yemeni pro-government forces advance into rebel-held Hodeidah. Photograph: Nabil Hassan/AFP/Getty Images

Attempts by the military coalition led by Saudi Arabia and the United Arab Emirates to retake the city from the rebels have been delayed after warnings from the UN and aid agencies that any damage to the port facilities could plunge Yemen – where three-quarters of the 28 million population are now reliant on aid to survive – into full-blown famine.

Fighting restarted in earnest last week, however, after US calls for a ceasefire at the end of November, as pro-government militias aim to seize as much ground as possible before hostilities are supposed to stop.

There have been at least 200 airstrikes, many on civilian neighbourhoods, and at least 150 people have been killed. Many residents are too poor to afford fuel or safe passage out of the city, but even those with the means to do so have been prevented from leaving by Houthi roadblocks on main roads. The passage of aid to the rest of the country has also been stalled by the fighting.

The latest violence has centred on eastern neighbourhoods and near a university campus just 4km (2.5 miles) from the vital port. Over the weekend, as first reported by the Guardian, the Houthis stormed the 22 May hospital in Hodeidah’s east, stationing snipers on the roof and panicking patients and staff who were terrified of being targeted in a coalition airstrike.

The fighting has already disrupted services at the hospital, which is one of only two properly functioning facilities left in the city, the Red Cross said.

Appearing in a televised address from the capital, Sana’a, on Wednesday night, the Houthi leader, Abdel Malik al-Houthi, said his fighters would not surrender their positions in the city.

In a joint statement on Thursday, several international aid agencies condemned the intense new violence in Hodeidah, calling it a “deeply disturbing development”, and calling on all parties to the conflict to cease the fighting and engage with the UN-sponsored peace process.

A new round of peace talks to end the war – which has killed an estimated 56,000 people and left 14 million on the brink of starvation – are scheduled for early December in Sweden.

At the UN, diplomats were working frantically to get agreement on a draft resolution by next Friday that would demand a ceasefire and the free flow of humanitarian aid. But there is concern that the US is demanding the draft include passages criticising Iran’s role in Yemen that might be sufficient to prompt a Russian veto. Sweden is leading calls for a full resolution and believes it now has the support of the British.

China has been pushing for a political declaration passed by consensus, something that has less legal force. The UN special envoy Martin Griffiths is due to brief the security council next Friday and on Thursday called on Saudi Arabia to end the violence.

He said: “Any military escalation does not help efforts to launch the political process. No one wants to see a catastrophe in Hodeidah.”

David Hale, an under-secretary in the US State Department, said “over 18 million Yemenis do not know where their next meal is coming from” and again called for an end to Saudi airstrikes in built-up areas. But he made no direct call for the Saudi-led coalition to end the assault on Hodeidah port.