Hundreds of thousands of Rohingya stranded in makeshift shelters in Bangladesh are facing a "catastrophe within a catastrophe" as the monsoon rains loom.
Preparations for the rains are in full force throughout the refugee camps in Cox's Bazar, which aid workers fear will bring devastation to the thousands of shelters precariously balanced on uneven land near the Burma border.
Those on the ground fear landslides and flooding will damage the tents, render the labyrinth of tiny, unpaved roads that crisscross the camps impassable, block access roads and potentially turn the settlement into a breeding ground for contagious disease.
But with the monsoon season usually stretching from the beginning of April, less than 0.5% of emergency funds has been secured through a global appeal, and the situation is being described as a race against time before the rains begin in earnest.
More than 650,000 people, mainly Rohingya, have fled neighbouring Burma since August last year - forming what is believed to be the world's largest refugee camp.
The ethnic minority group, which is mainly Muslim, rapidly crossed the border into southern Bangladesh reporting extreme violence and human rights violations.
The land is more vulnerable to the coming conditions after the widespread destruction of forested areas for fuel and building materials as a vast number of Rohingya settled spontaneously.
The camps largely consist of tens of thousands of bamboo and tarpaulin shacks without foundations.
According to the UN refugee agency UNHCR, an area the size of almost 120 rugby fields is landslide-prone, putting 23,000 people at serious risk, while more than 30% of the main camps and nearly 80,000 people could be hit by floods.
Almost half of the 7,275 hand pumps in the camps are in landslide or flood-prone areas, as are one quarter of the 19,000-plus latrines.
Aid workers have spent the past months reinforcing hills to prevent mudslides, building drainage systems in the lower levels of the camps to channel away dirty water and waste and strengthening buildings, such as health clinics and food distribution points, with concrete.
The first of the families deemed at greatest risk have begun to be relocated to higher ground, where charities are also stockpiling key aid materials in newly built warehouses.
Daphnee Cook, who is working for Save the Children in Cox's Bazar, said: "Save the Children is warning there's going to be a catastrophe within a catastrophe once the monsoon season hits.
"Our understanding is that over 100,000 Rohingya refugees are directly threatened by landslides and floods - that is quite a conservative estimate.
"As you know there are hundreds of thousands of refugees in those camps and every single person to some degree is placed in a precarious situation because their houses are made out of flimsy materials, their floors are made out of sand, which as we know the second it starts raining will turn into mud."
Many people approached by the Press Association in the camps expressed fears about the coming rains but said that they did not know where else they could go.
Minara Begum, 20, arrived in the Kerantoli camp six months ago with her young son. They fled Burma after her husband was shot dead.
She told PA: "I'm worried about the monsoon. If it rains the water can come into the tent so the tent can easily be destroyed.
"The tarpaulin can fly away and the rain can come into the house so we could easily get sick, and we don't have anywhere else to go.
"I'm really worried because I don't know how to keep my tent safe."
A potential health disaster may also be on the horizon, with the risk of latrines overflowing and contaminating clean water supplies.
Dominic McEvoy, who trained as a nurse in Ireland, has been working with Save the Children in the camps for two months.
The 32-year-old said: "We've just come through a crisis with diphtheria, and that seems to have gotten under control, as we approach the monsoon season we are expecting a big increase in diarrhoea-causing diseases, and diseases spread by mosquitoes, so we're trying to get mosquito nets out and also encourage better hand hygiene and access to clean drinking water."
Save the Children, the UN and other agencies are urging governments across the globe to fund a new 950 million US dollars response plan.
So far, they have raised 1.6 million US dollars - just 0.2% of the total.
Separately, an appeal launched by the DEC last August has raised £25 million, including £5 million from the UK Government - £8 million of which has been earmarked for use from April.
Parliament's International Development Committee, which visited the region earlier this year, has urged UK leaders to press for the Rohingya crisis to be prioritised at the Commonwealth Heads of Government meeting in London in April.