Hundreds of migrants stranded in Serbia have set off on foot from Belgrade towards the border with Hungary to protest against its closure for most people trying to reach the European Union.
Earlier in the Serbian capital, police intervened after the protesters clashed with other groups of migrants who were against the march. There were no reported injuries during the scuffles.
More than 6,000 migrants remain stuck in Serbia following Hungary's introduction this summer of strict limits on the number of asylum seekers allowed to cross into the EU-member country, and it has reinforced a razor-wire border fence with heavy patrols.
The so-called Balkan migrant route, used by nearly one million people fleeing wars and poverty last year, formally closed in March, forcing migrants to use alternative routes and pay smugglers to get them across.
On Tuesday, some 400 migrants chanted "Open Hungary borders" and held banners saying "We don't need food, water or nothing, we want you to open the borders" as they marched north in a long column from Belgrade along a road leading towards the Hungarian border some 120 miles away.
Most migrants appeared to be young men and boys who stand little chance of getting into Hungary or other EU nations.
Serbia said on Tuesday it would not erect a wire border fence but would deploy its army to seal off the borders with Macedonia and Bulgaria to stop migrants from coming in from those countries.
Hungary has refused to accept any of the migrants that the EU is trying to relocate from Italy and Greece and on Sunday voters there overwhelmingly approved any future mandatory quotas for accepting asylum seekers. The referendum was rendered invalid, however, because of a low turnout.
Meanwhile, Romanian police are investigating 16 Iraqi citizens, including six children, they found in two boats on the River Danube early on Tuesday for illegally crossing the border. The Danube forms the border between southern Romania and Bulgaria.
The migrants told police they had travelled through Turkey and then into Bulgaria and wanted to reach Germany. They said each family had paid 35,000 euro (£30,600).
The eight men, two women and six children will be handed over to Bulgarian authorities under the terms of a Romanian-Bulgarian agreement.