BELGRADE (Reuters) - Some 150 migrants, trapped in Serbia, set out on Friday to walk about 125 km (80 miles) to the Croatian border, demanding free and secure passage toward Western Europe, police said.

Police are following the group along the highway connecting Belgrade and the border.

“We started marching toward the border with Croatia. The camps are full, we sleep in parks, we cannot stand it any more,” said a migrant from Pakistan who gave his name as Habib.

According to the U.N. refugee agency, around 6,400 migrants from countries such as Syria, Iraq, Pakistan and Afghanistan are currently registered in Serbia, while local non-governmental organizations say their number is close to 10,000. They mostly arrive from Bulgaria and Macedonia.

Last month another group tried a similar protest march toward the Hungarian border, but eventually decided to return to Belgrade. Hungary has practically sealed its borders to migrants.

Last year a total of 579,518 migrants and asylum seekers were registered arriving in Serbia, out of more than a million who made it to Europe by land and sea.

A deal between Turkey and the European Union, struck in March, has largely shut off the flow of people reaching Greece and the Balkans, but Austria kicked off consultations with Balkan states this month to see what measures can be taken if the deal collapses.