Refugees have reportedly broken through a fence on the Macedonian and Greek border using a home-made battering ram.
BBC footage shows refugees ripping away barbed wire and pushing against the fence to get through.
Protesters clashed with authorities as they chanted “Open the border!” and threw stones at Macedonian police as a few hundred people managed to break through a gate at the border.
Police fired tear gas and stun grenades at the protesters, though no arrests or injuries have been reported. It is not known how many people crossed the border during the incident.
The gate has been used to let trains through at the border crossing and around 500 people forced their way past Greek police to reach it, authorities said.