Police say huge fire believed to have been started by disgruntled migrants, evacuated hours earlier.
The European Union has announced additional funding to help vulnerable migrants and refugees in Bosnia and Herzegovina, but urged the government there to rebuild a camp that burned down.
Brussels has denounced the condition for migrants in Bosnia, a candidate for EU membership, as “completely unacceptable”, and warned that lives are at risk.
Fire engulfed the Lipa migrant centre in northwestern Bosnia on December 23.
There were no casualties from the blaze but much of the infrastructure was destroyed.
The incident deepened a crisis over where to house thousands of migrants, as Bosnian authorities have failed to find new accommodation for the newly homeless.
In a statement, EU foreign policy chief Josep Borrell said Brussels was ready to add another 3.5 million euros ($4.2m) to its humanitarian support for Bosnia.
But he warned that 900 people were still exposed on the grounds of the destroyed camp, and that 800 more were without shelter in the region.
“The situation in Una Sana canton is unacceptable. Winter-proof accommodations are a prerequisite for humane living conditions, which need to be ensured at all times,” he said.
“Local authorities need to make existing facilities available and provide a temporary solution until Lipa camp is rebuilt into a permanent facility.”
Police believe the blaze was started by migrants to protest against the withdrawal of the UN’s International Organization for Migration (IOM), which had been running the camp.
The IOM had left, complaining that the accommodation – opened in April but without power or running water – was not fit to house people during the winter.
Bosnia lies on the so-called Balkans route used by migrants heading towards Western Europe as they flee war and poverty in the Middle East, Asia and in Africa. The country currently hosts some 8,500 migrants.
The living conditions of hundreds of homeless migrants in Bosnia are “completely unacceptable”, EU envoy Johann Sattler said on Saturday.
“Lives and basic human rights of many hundreds of people are seriously jeopardised,” added Sattler, the EU’s special representative in Bosnia, after a meeting with Bosnian Security Minister Selmo Cikotic.
Sattler met Bosnian Minister Cikotic on Saturday along with the German, Italian and Austrian ambassadors, according to a statement released by the EU delegation in Sarajevo.
The aim of the meeting was “to discuss urgent solutions for the extremely concerning migration situation”, the statement said.
The UN’s human rights office had already warned against “unacceptable suffering” of the migrants from the Lipa camp, calling for an urgent solution of the issue.