Syrian soldiers flash the victory sign on their tank in the town of Aftaris in Damascus' Eastern Ghouta countryside, Syria, on March 12, 2018. Syrian army captured on Monday the town of Aftaris in Eastern Ghouta, the latest town to be retaken by the army during the wide-scale offensive in that area, state news agency SANA said. (Xinhua/Ammar Safarjalani)

UNITED NATIONS, March 16 (Xinhua) -- UN Secretary-General Antonio Guterres said Friday that he "profoundly regrets that resolution 2401, concerning the cessation of hostilities throughout Syria, has not been implemented."

The UN chief said in a statement that he is "deeply concerned by the desperation shown by the people fleeing in a massive exodus from Eastern Ghouta and Afrin."

Eastern Ghouta has grabbed headlines recently amid a government resolve to recapture that sprawling area while at the same time allowing civilians to leave as around 400,000 people still live in that rebel-held enclave.

"I urge all parties to the conflict to fully respect international humanitarian and human rights law and guarantee the protection of civilians," he said, noting that "any evacuation of civilians must be safe, voluntary, and in strict accordance with protection standards under international humanitarian and human rights law."

Syrian civilians, evacuated from rebel-held areas in Eastern Ghouta, gather at a school in the Adra district on the northeastern outskirts of the capital Damascus on March 16, 2018. (Xinhua/AFP)

"It is also imperative that all those displaced are allowed to return voluntarily, in safety and in dignity, to their homes as soon as the situation allows it. I call on the Security Council to stand united and take concrete steps to urgently end this tragedy," he added.

The United Nations and its partners are fully mobilized to bring immediate life-saving relief to all those in need, the secretary-general said. "I call on all parties to ensure safe and unimpeded humanitarian access in all areas."

A Syrian tank aims at rebel positions in the town of Jisreen in the capital Damascus' Eastern Ghouta countryside on March 14, 2018. In the capital Damascus, the Syrian army continued its military offensive against the rebels in Eastern Ghouta, capturing new areas on Wednesday while securing the evacuation of civilians from areas in Eastern Ghouta. (Xinhua/Ammar Safarjalani)

"The reality on the ground across Syria demands swift action to protect civilians, alleviate suffering, prevent further instability, address the root causes of the conflict and forge, at long last, a durable political solution in line with resolution 2254," said the UN chief.

Thousands of civilians were fleeing from besieged enclaves on Friday as two major battles in the multi-sided war entered decisive phases, with hundreds of thousands of people trapped in the path of both assaults.

Civilians leave the city of Afrin, Syria, on March 14, 2018. Turkish President Recep Tayyip Erdogan on Wednesday expressed hope that Turkey's military and its allies would completely take Syrian Kurdish-held city of Afrin by Wednesday evening. Speaking to local administrators in Ankara, the president also said civilians in the city were being evacuated through a special corridor. (Xinhua)

The UN Security Council on Feb. 24 unanimously adopted resolution 2401 demanding a cease-fire of at least 30 days across Syria that would allow humanitarian access and urgent medical evacuations.