A fleet of buses has arrived in the sprawling refugee camp of Idomeni on Greece's northern border with Macedonia to take some of the estimated 12,000 people stranded there to nearby refugee camps.

Authorities sent 20 buses to transport 1,000 people to refugee camps set up in northern Greece. But refugees were reluctant to board as they had not been informed of where they would be taken.

Greece's border with Macedonia has been shut to refugees since earlier this month after a string of countries shut down what has become known as the western Balkan route which migrants used to go from Greece to central and northern Europe.

Those stranded in the camp and surrounding fields have been living in dire conditions in small tents pitched in muddy fields.