At least one person has died and eight more are missing after a boat carrying migrants and smugglers capsized on the Danube, Romania's border police said on Friday.

Sixteen migrants from various Asian and African countries, along with two smugglers, were on board the vessel which was trying to cross the river border with Serbia. The boat capsized near the south-western town of Drobeta-Turnu Severin late on Thursday, police spokeswoman Alexandra Gavan told AFP.

"Border police officers... noticed several persons in the waters of the Danube river asking for help," a police statement said, adding that "nine persons at risk of drowning were saved".

Those rescued were eight migrants from Syria, Iraq, Yemen, the Palestinian territories and one of the smugglers from Serbia, all of whom were suffering from hypothermia. "Shortly after the boat left Serbia, it started to take on water," the police statement said. "Scared, the migrants stood up and the boat capsized."

Romania does not belong to the EU's passport-free Schengen zone and it is rare that migrants attempt to enter the country. Hungary's strict closure of its border with Serbia has meant migrants and refugees have had to seek other ways of trying to reach western Europe.