Migrant men and boys, mostly from Afghanistan and Pakistan, remained in an abandoned customs warehouse by Belgrade's train station in freezing temperatures.
Aid groups have warned that migrants are at risk of exposure as extremely low temperatures and heavy snow gripped Serbia.
Migrants light fires inside the warehouse, and wrap themselves in blankets to keep warm.
The recent cold snap in Europe has now been blamed for at least 73 deaths, and seen the lowest temperatures for decades in some parts
Yesterday, authorities dug out stranded residents as heavy snow blanketed Eastern Europe and people struggled with travel delays, power outages and subzero temperatures.
Homeless people and migrants were among those most at risk.