Greece increased efforts Saturday to move thousands of migrants near the border with Macedonia to sheltered camps, as the spread of infection became a concern with two people in a sprawling tent city diagnosed with Hepatitis A.

Stranded in filthy conditions at a muddy tent city near the northern border town of Idomeni, at least 12,000 people, among them thousands of children, were waiting to cross the frontier, although Macedonia and other nations along the so-called Western Balkan route have closed their borders.

Scuffles broke out at the camp in recent days as destitute people scrambled for food and firewood, while many have been sleeping in the open, often in the rain amid low temperatures.

Greek authorities handed out leaflets in Idomeni Saturday informing people the main route to northern Europe was shut. The pamphlets urged them to move to buildings and hospitality centres across Greece that have been set aside for the purpose, according to a government official from the country's refugee crisis management coordination body.

"Our aim is not only to relieve Idomeni from the people, our aim is that no Idomeni (camp) even exists anymore. There are structures, why should people stay in the mud?" he said.

Leaflets would also be distributed in ports and on islands to discourage people from going up to Idomeni, the government official said.

"Greece will offer you accommodation, food and healthcare," read the leaflets which were written in Arabic, Farsi and Pashtun.

Deputy Defence Minister Dimitris Vitsas, in charge of coordinating Greek efforts to tackle the refugee crisis, said 400 people were moved from Idomeni to camps on Friday and the numbers would increase in the coming days.

"Many of them are waiting for a decision by the (EU) summit on March 17. We are saying that regardless of this decision, there are three camps very close (to shelter them)," he told Greek Mega television.

EU leaders and Turkey are due to meet again Thursday and Friday to seal a deal to try to stem illegal migrant flows from Turkey to Europe through Greece.

The squalid, overcrowded conditions of the camp in Idomeni have given rise to infections. A nine-year-old Syrian girl was Friday diagnosed with Hepatitis A, according to Greece's disease control agency.

The World Health Organisation says Hepatitis A is a virus transmitted through ingestion of contaminated food and water, or through direct contact with an infectious person. It is normally associated with lack of safe water or poor sanitation.

The girl was being treated in a stable condition, the agency said, adding that it had already taken action to prevent the disease spreading among migrants in Idomeni.

A second individual from Idomeni was diagnosed with Hepatitis A and transferred to a hospital on Saturday, a disease control official told Reuters.

To ensure water quality, seven water transportation vehicles, three deployed by the Greek army, started operating in Idomeni, the government said in an announcement late Saturday.

In the last 24 hours, 629 more people have arrived on Greek islands from Turkey, with the total number of migrants and refugees stuck in the country reaching about 41,000, government data showed.