Around 700 migrants have agreed to leave a squalid camp on Greece's border with Macedonia since violence broke out at the weekend when a group of migrants tried to storm the frontier, sources said Tuesday.

‘On Monday, seven buses carrying 300 people left Idomeni,’ where over 11,000 people had been camped out for weeks in the hope of the sealed border being re-opened, a police source told AFP.

On Tuesday, a further eight buses with a capacity of around 400 left the camp for nearby migrant reception centres, with four others readying to leave later in the day, an AFP journalist said.

Around 100 others -- some of them Iraqis - were taken to a camp near Veria, according to the charity that runs that facility.

Greece has for weeks been trying to convince the migrants to move to reception camps but until now they had refused to leave.

‘We can see more refugees are interested in leaving Idomeni,’ said Liene Veide, spokeswoman for the UN refugee agency UNHCR in Idomeni. ‘They don't feel comfortable here, they don't feel safe here, not at all anymore after the recent events.’

On Sunday, some 250 refugees and migrants were hurt when they tried to cross into Macedonia to continue their journey to northern Europe, with Macedonian riot police firing tear gas and rubber bullets to push them back.

Macedonia accused Greek police of failing to intervene to prevent around 3,000 people trying to illegally enter its territory, but Athens said Skopje had used ‘excessive force’.

The clash marked the latest bout of unrest at Idomeni, where thousands of migrants fleeing war, persecution and poverty in the Middle East and Asia found themselves stranded after Macedonia and other Balkan states denied them passage to Germany and other destinations in northern Europe.

Many of them are refugees from the wars in Syria and Iraq.

Sunday's violence broke out after Arabic-language leaflets distributed around the camp falsely suggested the border was about to open.

Greek Prime Minister Alexis Tsipras on Monday blamed foreign volunteers for ‘inciting’ migrants to storm the fence.

UNHCR's Veide said the flyers were ‘everywhere’.

‘We don't have any information who is exactly doing that, but definitely it's not the solution in this situation,’ she told AFP.

Greek police on Tuesday detained over a dozen volunteers for questioning before releasing them without charge, with the exception of a German national who was found in possession of a knife.

Efforts are also under way to peacefully clear another makeshift camp at the port of Piraeus housing some 5,000 migrants.

Around 1,000 of them agreed on Monday to relocate to a nearby camp at the industrial hub of Skaramangas.