Russian aerial bombardment in Aleppo
Residents inspect damage after airstrikes by pro-Syrian government forces in Anadan city, about 10 kilometers away from the towns of Nubul and Zahraa, Northern Aleppo countryside, Syria February 3, 2016 Reuters

World's rich nations pledged more than $10 billion to help war-ravaged Syria deal with the humanitarian crisis following a five-year war.

Reuters reported donor nations will pay $11 billion in aid to Syrians by 2020, while some other reports said the aid amount exceeds $14 billion.

A conference of rich nations in London agreed on the aid after peace talks a day earlier in Geneva collapsed.

The pledge came even as Russia accelerated its bombardment of Aleppo, helping President Bashar al-Assad's forces gain control over the key city. The Syrian opposition said it is losing grip on the city with Assad forced gaining control over most parts of the city.

Turkey has heavily criticized the Russian move saying Moscow was threatening the city with a "siege of starvation".

Russia retorted saying it suspected Turkey was planning a military incursion into Syria. There is a "growing number of signs of hidden preparation of the Turkish Armed Forces for active actions on the territory of Syria," Russia's defense ministry said.

Meanwhile, Saudi Arabia said it was willing to commit ground operations in Syria in a sign that the war against the Sunni Islamic militancy has gained a whole new perspective and significance in the region.

British Prime Minister David Cameron said the latest pledge of $5 billion comes on top of the $6 billion aide for Syrians in 2016, and the combined amount will be spent through 2020.

"We have combined a renewed effort to address the shortfall in humanitarian funding with a new approach to provide the education and jobs that will bolster stability in the region," Cameron said.

Syria's conflict, which started in the wake of Arab Spring movement in the region, has displaced more than six million people within the country while another four million refugees have fled the country.

'Siege of starvation'

An estimated 250,000 people have been killed in the conflict, while many of those who escaped death were reduced to eating grass and killing stray animals for survival, reports have said.

Turkey, which is hosting the biggest number of Syrian refugees, said up to 70,000 Syrians are trying to escape into Turkey now, fleeing the aerial bombardments on Aleppo.

"What they want to do in Aleppo today is exactly what they did in Madaya before, a siege of starvation," Turkish Prime Minister Ahmet Davutoglu said at the conference.

Hundreds of people were marching towards Turkey's Onucpinar border gate, carrying carpets, blankets and food on their backs, Reuters reported.