As the number of Rohingya refugees fleeing Myanmar edges towards half a million, the UN Refugee Agency is stepping up delivery of life-saving aid to desperate people camped out near two official refugee camps in south-eastern Bangladesh.

At the request of Bangladeshi authorities, "We are speeding up the distribution of plastic sheeting to get as many people as possible under at least minimal of protection from monsoon rains and winds," UNHCR spokesperson Andrej Mahecic said at a press briefing in Geneva today.

UNHCR site planners are on the scene to try to help organise a 2,000-acre (800-hectare) site allocated to new arrivals by authorities.

Known as the Kutupalong extension, the new site is next to Kutupalong camp, which houses Rohingya refugees who arrived over several decades. It is managed by the government and supported by UNHCR.

On Saturday the spokesperson said, "We plan to begin distribution of kitchen sets, sleeping mats, solar lamps and other essential relief items to an initial 3,500 families who have been selected by community leaders."

"Refugee volunteers and contractors are helping newly arriving refugees moving into emergency shelter, but it is vital that our site planners have the opportunity to lay out the new Kutupalong extension in an orderly way to adequately provide for sanitation and to make sure structures are erected on higher ground not prone to flooding."

Many of the estimated 420,000 refugees who have arrived in Bangladesh over the last 3.5 weeks have been taken in by families inside two official camps, Kutupalong and Nayapara, or are living in schools and other public buildings converted into communal shelters.

It is considered as a priority to get them – as well as many others in informal settlements – into Kutupalong extension, where UNHCR can support the government and partners in protecting and assisting them.

Once they move, the schools can also re-open for education for locals and refugees.

"We are working with authorities to have an access road built to make it easier to deliver tents, sheeting and essential relief items directly to people where they already are," Andrej said.