Turkey has opened its borders with Greece to more than 100,000 migrants and refugees in an apparent attempt to pressure the EU over the crisis in Syria.

President Recep Tayyip Erdogan announced he was allowing people through its crossing points on Friday following an escalation of fighting in Idlib province and the death of 33 Turkish soldiers in an airstrike.

Almost immediately thousands of people began massing in the border zone between the two countries, prompting Greek authorities to fire tear gas and stun grenades to push them back from the fences.

On Sunday evening, Turkish interior minister Suleyman Soylu announced that 100,577 people had left Turkey through the city of Edirne, more than double the number that had passed through by end of Saturday.

The huge increase in numbers has increased the pressure on Greek authorities at crossing points along the 212km border.

Monitors for the UN’s International Organisation for Migration said at least 13,000 people had gathered at the formal border crossing points at Pazarkule and Ipsala as well as other informal crossings.

Syrian regime bombards Idlib Show all 23 1 /23 Syrian regime bombards Idlib Syrian regime bombards Idlib Members of the Syrian Civil Defence, also known as the White Helmets, recover a wounded boy from the rubble of a building following a regime air strike on a vegetable market in Syria's last major opposition bastion of Idlib AFP via Getty Syrian regime bombards Idlib The regime air strikes killed at least nine civilians, striking bustling areas of Idlib city AFP via Getty Syrian regime bombards Idlib An injured woman waits to receive treatment at a makeshift hospital AFP via Getty Syrian regime bombards Idlib Syrian Civil Defence, also known as the White Helmets, searching through the rubble of a building AFP via Getty Syrian regime bombards Idlib A Syrian boy is evacuated AFP via Getty Syrian regime bombards Idlib A drone picture taken on January 15, 2020, shows members of the Syrian Civil Defence, also known as the White Helmets, searching through the rubble of a building at the site of a regime airstrike on Syria's last major opposition bastion of Idlib - Regime air strikes on Syria's last major opposition bastion killed at least nine civilians, striking bustling areas of Idlib city despite a fresh Russian-sponsored truce, a war monitor said. At least 20 other civilians were wounded in the raids that hit a vegetable market and repair shops in Idlib, capital of the jihadist-held province of the same name, said the Syrian Observatory for Human Rights. (Photo by Omar HAJ KADOUR / AFP) (Photo by OMAR HAJ KADOUR/AFP via Getty Images) OMAR HAJ KADOUR AFP via Getty Images Syrian regime bombards Idlib The wreckage of a car AFP via Getty Images Syrian regime bombards Idlib A Syrian boy cries as he is evacuated AFP via Getty Images Syrian regime bombards Idlib Rescuers search for survivors EPA Syrian regime bombards Idlib A drone picture taken on January 15, 2020, shows members of the Syrian Civil Defence, also known as the White Helmets, searching through the rubble of a building at the site of a regime airstrike on Syria's last major opposition bastion of Idlib - Regime air strikes on Syria's last major opposition bastion killed at least nine civilians, striking bustling areas of Idlib city despite a fresh Russian-sponsored truce, a war monitor said. At least 20 other civilians were wounded in the raids that hit a vegetable market and repair shops in Idlib, capital of the jihadist-held province of the same name, said the Syrian Observatory for Human Rights. (Photo by Omar HAJ KADOUR / AFP) (Photo by OMAR HAJ KADOUR/AFP via Getty Images) OMAR HAJ KADOUR AFP via Getty Images Syrian regime bombards Idlib A Syrian boy grimaces in pain after he was wounded in the airstrikes AP Syrian regime bombards Idlib A Syrian youth stands at the site of a regime air strike in Ariha town AFP via Getty Syrian regime bombards Idlib Rescuers search for survivors under the rubble of a collapsed building EPA Syrian regime bombards Idlib A Syrian walks on the rubble of a building following a regime air strike on Ariha town in Syria's last major opposition bastion of Idlib on January 15, 2020. - Regime air strikes on Syria's last major opposition bastion killed at least nine civilians Wednesday, striking bustling areas of Idlib city despite a fresh Russian-sponsored truce, a war monitor said. (Photo by Omar HAJ KADOUR / AFP) (Photo by OMAR HAJ KADOUR/AFP via Getty Images) OMAR HAJ KADOUR AFP via Getty Syrian regime bombards Idlib Firefighters try to extinguish flames EPA Syrian regime bombards Idlib Emergency services look for survivors AP Syrian regime bombards Idlib Emergency services look for survivors after airstrikes in the city of Idlib, Syria, Wednesday, Jan. 15, 2020. Syrian government warplanes struck a market and an industrial area Wednesday in the last territory in the hands of rebel groups in the country's northwest, killing at least 15 people, opposition activists said. (AP Photo/Ghaith Alsayed) Ghaith Alsayed AP Syrian regime bombards Idlib A boy wounded in airstrikes is treated in a hospital AP Syrian regime bombards Idlib Syrian White Helmet civil defense workers extinguish a burning car Syrian Civil Defense White Helmets via AP Syrian regime bombards Idlib A Syrian walks on the rubble of a building AFP via Getty Syrian regime bombards Idlib People walk past destruction by the government airstrikes in the town of Ariha, in Idlib province, Syria, Wednesday, Jan. 15, 2020. Syrian government warplanes struck a market and an industrial area Wednesday in the last territory in the hands of rebel groups in the country's northwest, killing at least 15 people, opposition activists said. (AP Photo/Ghaith Alsayed) Ghaith Alsayed AP Syrian regime bombards Idlib People walk past destruction by the government airstrikes in the town of Ariha, in Idlib province, Syria, Wednesday, Jan. 15, 2020. Syrian government warplanes struck a market and an industrial area Wednesday in the last territory in the hands of rebel groups in the country's northwest, killing at least 15 people, opposition activists said. (AP Photo/Ghaith Alsayed) Ghaith Alsayed AP Syrian regime bombards Idlib People look at destruction by the government airstrikes in the town of Ariha, in Idlib province, Syria, Wednesday, Jan. 15, 2020. Syrian government warplanes struck a market and an industrial area Wednesday in the last territory in the hands of rebel groups in the country's northwest, killing at least 15 people, opposition activists said. (AP Photo/Ghaith Alsayed) Ghaith Alsayed AP

“Most of those on the move are men but we are also seeing many family groups travelling with young children,” said IOM Turkey chief Lado Gvilava.

“We’re distributing meal boxes and other basic supplies in the city but the temperatures are dropping to nearly zero and the wind is quite bad so we’re concerned about these vulnerable people who are exposed to the elements.”

Other migrants attempted to make the short sea crossing from the Turkish coast to the Greek islands. At least three dinghies carrying migrants arrived on the Greek island of Lesbos on Sunday morning.

Greek deputy defence minister Alkiviadis Stefanis said there were around 9,600 attempts to illegally cross Greece’s border during the night.

Officials said they arrested 66 migrants on Friday and 70 on Saturday. Seventeen of those, all Afghans, were jailed for entering the country illegally, the first such sentences since 2014.

​Under a €6bn (£5bn) deal in 2016, Turkey agreed to stem the tide of refugees to Europe in return for financial aid.

However, nearly 950,000 displaced civilians have been pushed towards the Syrian-Turkish border amid a military escalation in Idlib province.

On Saturday, Mr Erdogan said Turkey would not stand in the way of refugees and migrants already in the country who hope to head to Europe.

“We will not close the gates to refugees,” he said. “The European Union has to keep its promises. We are not obliged to look after and feed so many refugees.”