Refugees face violence and disease as they travel across the Red Sea hoping to find work in the Gulf states.

Yellow and purple headscarves and patterned dresses made a jarring contrast with the camouflage uniforms worn by soldiers milling around a bullet-ridden checkpoint in the southern Yemeni city of Aden. 

It was 8am, and the sun was already hot. The family of six – four women and two men from Ethiopia, across the Red Sea – had already walked eight miles (13km) so far that morning. They stopped to ask the soldiers for water before continuing on their journey.

“We didn’t know about the fighting in Yemen before we came on the boat last night,” said one of the group, Abdul Saleh Tayeb. “But we are looking for money. We have to go to Saudi Arabia.” They still had around 1,000 miles (1,400km) through disputed territories, mountain passes and scorching desert to go. 

The Guardian met Tayeb and his family during a visit to Yemen last September, swapping contact details, although their phone number has not worked since then. The family are some of the around 138,000 people from the Horn of Africa who made the dangerous journey across the Red Sea to Yemen last year in the hope of reaching the Gulf states and finding employment. 

According to the International Organisation for Migration (IOM), as Europe has cracked down on routes over the Mediterranean from Turkey and Libya, the journey to Yemen is now the busiest maritime migration route in the world. Young men in an Aden park told the Guardian they paid 15,000 Ethiopian birr (£354) for the journey.

Almost none of the new arrivals from Ethiopia and Somalia know that war has raged in Yemen for the least five years, impeding their onward journey, or that torture and rape could await them at the hands of smugglers and traffickers. Now, aid agencies are warning that funding shortfalls and cuts and the spread of coronavirus in the country leaves Yemen’s hidden migrant population even more vulnerable. 

“As well as Yemenis displaced by the conflict, we are also trying to help migrants who have no money, no support networks, nothing when they get here,” said Jean Nicholas Beuze, the UN refugee agency’s representative to Yemen. 

“As of [June] we will have to stop cash payments that help people buy clothes and medicine, and by August we will run out of even the most basic shelter equipment like plastic sheeting. 

“Responses take planning: we’re not talking about 2021 here, we’re talking about this week. Everyday this is pushing more people into deep poverty. We are worried about an increase in things like survival sex and marrying off young children.”

According to the UN, Yemen is experiencing the world’s worst humanitarian crisis. Almost 80% of the 29-million-strong population is dependent on aid to survive, and a blockade imposed on Houthi-rebel held areas by the Saudi and Emirati-led coalition fighting to restore Yemen’s UN-backed government has led to cholera epidemics and severe malnutrition among children. The combined death toll from fighting and disease at the end of 2019 was estimated at 230,000 people. 

Western governments, including the UK and the US, have been heavily criticised for their role in the devastation, which includes selling arms and providing technical expertise to the Gulf-led coalition. 

That has not stopped some donors, including the US, cutting funding to UN programmes in Yemen at the beginning of the year because of Houthi attempts to consolidate control over the management and distribution of resources. The UK has so far pledged £18m in aid to Yemen for 2020, which is less than 10% of what it provided last year. 

The cuts and funding shortfalls have already led 75% of UN programmes to shut their doors or reduce operations: the World Food Programme (WFP) has halved food deliveries and UN-funded health services have faced cutbacks in 189 out of 369 hospitals nationwide. 

Thirty out of 41 major programmes will be forced to close down completely even as Covid-19 overwhelms what is left of Yemen’s collapsed health system. Yemen only has 323 confirmed cases of the virus, but there are reports of deaths from Covid-19 symptoms from around the country. 

World Health Organization predictions estimate that even if the pandemic response is well-managed, at least 42,000 Yemenis will succumb to the virus. A worst-case scenario could see 93% of the around 30-million-strong population infected.

For the first time, Saudi Arabia is hosting a new UN donor pledging conference on Tuesday, but many aid workers and doctors fear that whatever new assistance arrives, irreparable damage has already been done. 

“We have worked through crises in the war before but since coronavirus broke out it’s unlike anything I’ve seen before,” said Dr Ishraq Alsubai, spokeswoman for Yemen’s national committee to combat the coronavirus.