“The situation for people trapped in eastern Aleppo remains of the gravest concern,” said Stephen O’Brien, noting that he is aware of the measures proposed on Thursday by the Russian Federation to set up humanitarian corridors.

Media reports suggest that Russia has proposed establishing several so-called “exit corridors” that would allow for the distribution of food, as well as provide an opportunity for civilians to flee the city.

While underscoring that the situation is so dire that all options must be considered,  O’Brien stressed that it is critical that the security of any such corridors is guaranteed by all parties and that people are able to use them voluntarily.

“No one can be forced to flee, by any specific route or to any particular location. Protection must be guaranteed for all according to the principles of neutrality and impartiality,” he stated.

 O’Brien said that his proposal for 48-hour humanitarian pauses to enable cross-line and cross-border operations is what humanitarian actors require. This would ensure that relief workers are able to see for themselves the dire situation of the people, assess their needs, adjust to logistical constraints and assist people where they are now with their life-saving and protection needs.

“In any event, all parties are required and obliged, under long-established and accepted international humanitarian law, to allow safe, unimpeded, impartial and immediate humanitarian access for civilians to leave and for aid to come in,” he said.

Earlier in the week,  O’Brien, who is also the UN Under- Secretary-General for the Coordination of Humanitarian Affairs, warned the Security Council that the clock is ticking and the parties, and those with influence, “must act now” to establish a weekly, 48-hour humanitarian pause so much-needed assistance could be provided to the people trapped in Aleppo.

“This must be a full United Nations call – not just from me as the UN's humanitarian chief – this has to come from you, the Security Council,” he said.

Meanwhile, the UN Special Envoy for Syria, Staffan de Mistura, spoke to reporters in Geneva on Thursday and told them that fighting on the ground is impeding humanitarian aid in the country. Noting “serious concern” about the situation in Aleppo, saying that the city is “de facto besieged,” because it is almost completely encircled militarily.

“The clock is therefore ticking; there is no doubt about that. If Aleppo becomes a […] major besieged area – and we are very close to that – we would have a huge number of additional besieged – humanitarian wise- people in the country, when we were actually having a reduction,” he said.

On the humanitarian side, the Special Envoy is urging the two co-chairs of the International Syria Support Group (ISSG), the Russian Federation and the United States, to expedite discussions on how to reduce the violence, along the lines of the meetings in Moscow and then in Laos, particularly between Russian Foreign Minister Sergey Lavrov and United States Secretary of State John Kerry. Along with Russia and the US, the ISSG comprises the UN, the Arab League, the European Union and 16 other countries that have been working on a way forward since late last year.

 de Mistura said that his Deputy Special Envoy, Ramzy Ezeldine Ramzy, will head to Damascus in the next few days to discuss with the Syrian authorities some ideas that the Office of the Special Envoy has developed in order to facilitate the launch in August of the intra-Syrian talks.

The Special Envoy in the meantime is proceeding to Tehran to talk to the Iranian authorities.