NEW DELHI: Syrian rebels have left the last areas they held in Aleppo's old city, the United Kingdom based Syrian Observatory for Human Rights has said. The rebels, who have held the areas around Aleppo’s ancient citadel for more than four years, retreated after intense fighting, as the Syrian army moved to regain control of the city. With the latest success, the Syrian army now has control of over two-thirds of Aleppo.

The developments present a huge victory for the government forces, as Aleppo is the last urban rebel stronghold in the country. Once Syria’s commercial powerhouse, Aleppo has seen nothing but destruction and ruin since 2012, as the city came to be divided between a government-held west and rebel-controlled east. In the years that followed, Aleppo has suffered the gravest casualties, with a mounting civilian toll as people were trapped between the crossfire.

Both sides -- government and rebel groups, each supported by foreign powers -- have faced criticism and allegations of human rights violations in the years of conflict. Food supplies, water, healthcare and other basic amenities have been virtually cut off, as the death toll continued to climb.

The Syrian government, with Russian air support, has seen some of its biggest successes against the rebels in Aleppo in recent weeks. State media said on Tuesday that government forces won control of seven districts including the strategic Shaar neighbourhood, bringing under government control three quarters of former rebel held territory. The Syrian army said it had also taken over other areas to the east of the Old City, including Marja and Karm al-Qaterji, bringing it closer to cutting off another pocket of rebel control.

The rebels, on their part, deny the developments, but have said that the Syrian army and its allies were trying to break through and that fighting was ongoing.

The Syrian forces success comes with a heavy war toll, with over 341 people killed in east Aleppo, including 44 children -- according to the SOHR. Rebel fire, in turn, has killed at least 81 people, including 31 children, in the same period.

Given the gravity of the situation faced by civilians stuck in the cross fire, world powers have attempted at various points to reach a ceasefire or other working solution. These repeated attempts have continually failed, with the latest attempt at talks between Russia and the US -- scheduled for Wednesday -- also looking set to collapse. Russia had announced talks with the US in Geneva on Wednesday to organise a rebel withdrawal before putting in place a ceasefire. However, Russian Foreign Minister Sergey Lavrov recently accused Washington -- who Russia maintains backs the rebels -- of backtracking. "It looks like an attempt to buy time for the rebels to have a breather, take a pause and replenish their reserves," Lavrov said.

US Secretary of State, John Kerry, however denied the charge. The US, in turn, has accused Russia of heavy civilian casualties and blamed Moscow for stalling attempts at implementing a ceasefire, most recently after Russia and China blocked a UNSC resolution calling for an immediate ceasefire on Monday.

Syria, on its part, has said that no ceasefire can be implemented till the rebels guarantee withdrawal. "Syria will not leave its citizens in east Aleppo to be held hostage by terrorists, and will exert every effort to liberate them," a Syrian foreign ministry statement said.

The rebels thus far have rejected any talk of leaving the city, let alone guaranteeing a withdrawal.