A group of migrants at Greece's border with Macedonia have blocked a rail line in protest at Macedonia's refusal to let them in to continue their route toward Western Europe.

The group lay down on the Greek side of the train track Thursday morning, preventing a freight train that had just crossed from Macedonia from continuing its journey south.

Some 10,000 people are blocked at the border. Macedonian authorities have said they will only let in as many people as the next country on the route, Serbia, takes. Greek police said that in the 24 hours to 6 a.m. Thursday, 500 people were allowed to cross.

Some of those who were allowed into Macedonia were then sent back by authorities there because of problems with their papers.