Thousands more Syrians rush toward Turkey to flee fighting

Turkey is preparing for a new influx of refugees fleeing a major offensive by Syria's Russian-backed regime, with tens of thousands of Syrians camped out near a closed border crossing.

The United Nations said some 20,000 people have gathered at the Bab al-Salam crossing, hoping to reach Turkey, which already hosts more than two million refugees from the bloody conflict.

The Syrian Observatory for Human Rights for its part estimated some 40,000 people had been forced to leave their homes since last Monday.

Turkish authorities were working to free up space within the existing camps along the Syrian border to accommodate the new arrivals.

Opposition forces and some 350,000 civilians were inside the rebel-held Aleppo city, which was targeted in the government offensive.

An AFP correspondent saw trucks carrying parts for tents on Friday to the refugee camp close to the border gate on the Turkish side which faces the Bab al-Salam crossing on Syrian soil.

At least four Turkish aid trucks were also seen returning to Turkey after making deliveries of food to the Syrian side of the border.

Turkey's Disaster and Emergency Management Authority (AFAD) said in a statement that it had finalised preparations for a possible influx.

"The attacks and bombings by the Russian planes and the Syrian regime have left our brothers with nowhere else to go," Turkish Prime Minister Ahmed Davutoglu said in a televised speech.

The attacks and bombings by the Russian planes and the Syrian regime have left our brothers with nowhere else to go - Turkish Prime Minister Ahmed Davutoglu

Turkish authorities increased security at the crossings and the pro-government A Haber news channel said all police and military leaves were cancelled.

The international aid group Mercy Corps said that among those fleeing toward Turkey were residents of rebel-held areas of Aleppo who feared they would soon be besieged by government forces, while others were running from troops advancing in rural areas.

The Syrian government offensive began earlier this week in rural areas north of Aleppo, the provincial capital, and appears aimed at eventually encircling the city.

Forces loyal to President Bashar al-Assad captured several towns and villages, driving a wedge into rebel-held areas and cutting off a supply road to Turkey.

Once Syria's thriving commercial centre, Aleppo has been divided since 2012 between government- and rebel-controlled districts.

A government siege of rebel strongholds could isolate tens of thousands of civilians and would deal a devastating blow to the morale of groups fighting to topple Assad for the last five years.

It does look like a terrible humanitarian situation inside of Syria and it is poised to get worse. And that is something that we continue to be quite concerned about - White House press secretary Josh Earnest

White House press secretary Josh Earnest expressed concern that government forces backed by Russia threatened Aleppo.

"It does look like a terrible humanitarian situation inside of Syria and it is poised to get worse. And that is something that we continue to be quite concerned about," Earnest said.

Mercy Corps, which has been delivering food to civilians in northern Syria, said it had to stop distributions in opposition-held areas of Aleppo earlier this week because the sole access road became too dangerous.

The Russian airstrikes north of Aleppo have "hugely increased" in the past two weeks, said Rae McGrath, head of Mercy Corps operations in Turkey and northern Syria.

The human rights advocacy group Amnesty International urged Turkey to admit the displaced.

Turkey "must not close its doors to people in desperate need of safety," said Amnesty's Global Issues Director Sherif Elsayed-Ali.

Turkish TV showed Syrians walking between long rows of large white tents at Bab al-Salam, and Davutoglu said tens of thousands more were on the move.

We are asking that Turkey looks after us and opens its doors to us... There are sick people, children, women, and wounded people. They came to the border in difficult conditions

Abdulgani Fettah told Turkey's state-run Anadolu Agency that he escaped to the border after his hometown of Bab came under heavy bombardment.

"We are asking that Turkey looks after us and opens its doors to us," Fettah said.

"We are in difficulty because of the cold. There are sick people, children, women, and wounded people. They came to the border in difficult conditions."