Macedonia’s border has been sealed for the last 10 days, with at least 12,000 migrants camped in the Greek village of Idomeni hoping to travel further north but finding their way barred.
Large numbers of people left the camp, where conditions are primitive, walking for hours in heavy rain and wading across a river by the Macedonian border.
They passed a rope across it and formed a human chain so they could cross, with some carrying children on their shoulders. After crossing, hundreds found a gap in a barbed wire fence that Macedonia has built along its border to deter migrants.
Macedonian police said three people, presumed to have been migrants, drowned while trying to cross another river by the Greece border.
The migrants and refugees, many of whom come from war zones in Syria and Iraq, want to head north to wealthier European Union nations such as Germany.
The EU is trying to stop the flow of migrants into Europe, which reached more than a million in 2015.
EU leaders and Turkey are due to meet this week to seal a deal to try to stem illegal migrant flows from Turkey to Europe through Greece, having held discussions last week.
Refugees and migrants travel two billion miles in 2015
Under this agreement, all “irregular” migrants who have travelled from Turkey to Greece would be returned to Turkey.
In return, Turkish Prime Minister Ahmet Davutoglu has proposed that EU countries resettle an equal number of Syrian refugees who are living in Turkey.
He is also calling for a doubling of EU aid to support the 2.5 million migrants and refugees in Turkey, faster progress on easing visa restrictions for Turks, and talks on Ankara’s application for EU membership.
European Council President Donald Tusk described the talks as the “most promising moment” so far in efforts to deter migrants from crossing from Turkey to Greece by boat.
The EU is in the midst of its biggest migrant crisis since World War Two. Several European countries are restricting the numbers of migrants crossing their borders.