Several hundred migrants are camping along Serbia's borders, exposed to harsh winter weather and sleeping rough in make-shift shelters as they look for a chance to cross into neighbouring European Union countries.
Thousands have been stranded there since countries along the so-called Balkan migrant route closed their borders in March 2016 to stem the flow into the EU.
Officials and aid groups say that some 300-400 migrants are currently along Serbia's borders with neighbouring EU countries Croatia and Hungary, looking for an opportunity to cross over.
Many have lived out in the open for months, often trying dozens of times to cross and facing push backs by police.
An additional 4,000 migrants are living in asylum camps in Serbia, stranded in the Balkan country after borders closed.