A group of United Nations Security Council members on Wednesday urged Russia to stop its intense bombing in support of Syrian regime forces and allied militia that they said has exacerbated an already dire humanitarian situation.

The 15-member Security Council met behind closed doors at the call of New Zealand and Spain, which alongside Britain and France pressed Russia to allow humanitarian aid in areas under siege and implement a ceasefire.

Since the Syrian regime moved to encircle the city of Aleppo and cut off a key supply line to the north some 50,000 displaced Syrians remain at the Turkish border. The UN has warned thathundreds of thousands of people are at risk of being cut off from humanitarian aid.

"Russia's airstrikes have been a direct cause of this crisis around Aleppo," New Zealand's UN ambassador, Gerard van Bohemen, told reporters after being briefed by the UN's humanitarian chief. "We do call on them to show decency and cooperate with the UN."

The Red Cross said the fighting was putting "enormous pressure" on civilians.

"The temperatures are extremely low and, without an adequate supply of food, water and shelter, displaced people are trying to survive in very precarious conditions," said Marianna Gasser, head of the International Committee of the Red Cross in Syria.

Another try for talks in Munich

International and regional powers including the United States, Russia, Saudi Arabia and Iran were set to meet in Munich on Thursday in a bid to revive UN-backed peace talks that collapsed as soon as they started last week .

Syrian opposition members have said they would not start talks with the regime until Russia and Syrian forces halt their offensive, allow humanitarian aid into besieged towns and release prisoners. The United States has reportedly pressed the Syrian opposition to sit down with the regime without preconditions, even as it engages with Russia to implement a humanitarian ceasefire.

"The [Syrian] regime and its allies cannot pretend they are extending a hand to the opposition while with their other hand they are trying to destroy them," French UN Ambassador Francois Delattre told reporters on Wednesday. "Let me be clear about it: It's not a favor that we are asking to the Syrian regime and its allies, it's their obligation."

On Thursday, Russia may put forward a proposal to start a ceasefire and allow humanitarian access as of March 1, according to one Western official familiar with the talks.

Changing reality on the battlefield

That date, however, would still give Syrian forces and the Russia air force time to alter the battlefield situation in Aleppo city and the northern countryside, strengthening the regime's bargaining position going into any talks.

Russian UN Ambassador Vitaly Churkin on Wednesday was unapologetic about the offensive in Aleppo and accused other Security Council members of exploiting the humanitarian crisis for political purposes.

"They rather crudely use humanitarian matters in order to play, we believe, a destructive role as far as the political process is concerned," said Churkin. "This propagandistic use of the Syrian humanitarian file is not going to deter Russia from doing the humanitarian work we are doing with the Syrian government."

Churkin reiterated Moscow's stance that Russia was in Syria at the invitation of the legitimate government in Damascus, noting that "changes in balance on the ground... should be taken as logical development in any armed conflict."

cw/sms (AFP, AP, Reuters, dpa)