The Ikea Foundation on Saturday insisted that its refugee shelters are safe, a day after the Swiss city of Zurich said it no longer would use the units after discovering they posed a fire hazard.

Zurich announced Friday that a fire safety test had revealed the Ikea ready-to-assemble refugee shelters were "easily combustible."

The city made its announcement just hours after unveiling the 62 units it had purchased, lamenting that it now needs to find an alternative for housing 250 asylum seekers by early January.

The northern Swiss canton of Aargau followed suit, saying it no longer planned to house 300 asylum seekers in the shelters over the next few months.

Maerta Terne, a spokeswoman for the Better Shelter project, born out of a collaboration between the Ikea Foundation and the UN refugee agency, told AFP she could not comment on the Swiss safety test before seeing a "translation of the report on the results and the method used."

However, she stressed the tests against European safety standards "on the walls and covering panels showed that the material held a security level superior to that required for temporary shelter."

Zurich said it had relied on safety information from the Swedish study and from UNHCR before purchasing the shelters.

But regional authorities had requested a new test after learning that a German report this week raised concerns about the accuracy of the Swedish study.

"Safety is of course a priority and we'll be looking carefully at the fire study reports," UNHCR spokesman Adrian Edwards told AFP.

According to Better Shelter, the UN agency has ordered for its operations this year 10,000 of the 17.5-square-metre (188-square-foot) easy-to-assemble shelters, which come in Swedish furniture giant Ikea's famous flatpacks.

The units have already been deployed by the hundreds in refugee camps in Chad, Ethiopia and Iraq, and some 1,200 were recently assembled in Greece, as the country struggles to deal with a heavy influx of migrants and refugees, Better Shelter said on its website.