Greek police on Wednesday restarted an operation to move migrants out of Idomeni, the squalid tent city where thousands fleeing war and poverty have lived for months. A police source said they hoped to transfer "roughly the same number" of migrants as on Tuesday, when they carried them in more than 2,000 buses to newly opened camps near Greece's second city Thessaloniki, about 80 km to the south. Some 8,400 people are living in the muddy and dirty camp on the Macedonian border, which has become a potent symbol of human suffering and chaos as Europe struggles with its worst migrant crisis since World War II. The dawn operation, involving some 700 police backed by helicopter, "is continuing normally and calmly, like yesterday," said the police officer, who declined to be named. Most of those at the camp are fleeing war and misery in the Middle East and Asia and the group transferred Tuesday included 662 Syrians, 1,273 Kurds and 96 Yazidis. "We try to separate nationalities to avoid friction between them," said another police source. Around 100 migrants refused to enter the new center on Tuesday and headed off by foot to downtown Thessaloniki. Non state-run media were again kept at a distance during Wednesday's operation. On Tuesday, ERT state television and state news agency ANA showed migrants patiently queuing up to board buses and being driven away, some waving at the camera. Many carried their belongings in huge bin bags, while others piled possessions into pushchairs. It will take a week to complete the operation to clear all 8,400 people living there, the government said. "It is all going well, perhaps better than we expected. The migrants are tired and no longer expect the borders to be reopened," a police source said Tuesday. Oxfam urged Athens to guarantee migrants have "full access" to information and medical treatment. "Vulnerable people, the majority of whom are women and children, are being treated like pawns in a chess game," the NGO added. The Greece-Macedonia border is one of several in the Balkans closed since mid-February as countries on the migrant route have sought to halt the influx. And the transfer comes after a brutal winter of freezing rain and mud which saw many people trying to force their way across the border, sometimes resulting in violent encounters with Macedonian police. At its height, more than 12,000 people crammed into Idomeni, a camp that aid groups originally opened last year to accommodate just 2,500 people during what was at the time a short procedure to cross the border. The camp exploded in size after Balkan states began closing their borders in February to stem the human tide seeking new lives in northern Europe. Officials have said 6,000 spots are available at reception centers near Thessaloniki and elsewhere. Many of the camp's residents are women and children desperate to be reunited with male relatives who have forged ahead on their own — often with the aid of smugglers — hoping to find a place of refuge for their families in richer EU states than debt-hit Greece. Migrants are wary of relocating to organized camps away from the border or Athens because it could be harder to find people-smuggling contacts. There are currently more than 54,000 migrants stranded in Greece, according to government estimates. Protesting migrants have repeatedly blocked rail traffic between Greece and Macedonia, hampering trade between the two countries. So far this year, the International Organization for Migration says an estimated 190,000 migrants and refugees have entered Europe by sea, arriving in Italy, Greece, Cyprus and Spain. Another 1,359 have died en route. A controversial deal between Turkey and the EU came into force in March aiming to halt the flow of people to Greece. But Turkish President Recep Tayyip Erdogan warned Tuesday that parliament would block laws linked to the deal if Ankara is not granted its key demand of visa-free travel.