Istanbul - The evacuation of Aleppo should be completed within the next two days, Russian and Turkish foreign ministers say, following a rare breakthrough and show of unity by world powers over Syria that allows UN monitors to observe the operation.A total 37 500 evacuees have so far left the war-torn Syrian city and the goal is to complete all evacuations by Wednesday, Mevlut Cavusoglu, Turkish foreign minister, wrote on Twitter on Tuesday.The evacuation of of Aleppo would be complete in a maximum of two days, Sergey Lavrov, Russian foreign minister, said.Lavrov said that Russia, Iran and Turkey had used their influence to make the evacuation happen and that the 19-member International Syria Support Group including Saudi Arabia, Egypt and the US had not been able to enforce its decisions.Cavusoglu is currently in Moscow holding talks with his Russian and Iranian counterparts to discuss the future of Syria.The Syrian government has authorised the United Nations to send an additional 20 expatriate staff to east Aleppo, where they will monitor the ongoing evacuation of thousands of people, a UN spokesperson said."This will almost triple the number of international staff currently deployed to Aleppo," Jens Laerke announced in Geneva."The task is to monitor and observe the evacuations."The UN Security Council on Monday unanimously called for UN officials and others to observe the evacuation and monitor the safety of civilians.MonitorsThe UN staff, already in its Damascus office, will travel to Aleppo "as soon as possible", Laerke said.Aleppo, Syria's second city, was once a cultural and economic hub before being split between government and rebel control in late 2012. Al Jazeera's Charles Stratford, reporting from Reyhanli in neighbouring Turkey, said there were concerns, however, about "the kind of access" UN monitors would be granted once they are in Syria."There are reports of harassment by some of the Iranian-backed militias in that area," he added. "And of course ... there are concerns about how rebel forces may co-operate."According to UN aid partners, the number of people who had arrived in Idlib - where Aleppo evacuees are being taken - was around 19 000, the UN's Laerke said."We do not have independent UN access to the busses, so we are not able to enter and access people; that does not take away from the protection concerns that we do have and continue to have," he said.InjuredAbout 43 unwell people were medically evacuated from east Aleppo on Monday, bringing the total to 301 since last Thursday, according to Tarik Jasarevic, the World Health Organisation's spokesperson.The vast majority have trauma injuries. The sick and wounded include 67 children, Jasarevic said.The UN refugee agency UNHCR said there was no sign of a heavy influx of people fleeing Aleppo into neighbouring Turkey."All the borders of Syria are very tightly managed at present. People, we understand, are being allowed to cross into Turkey when they come. But I think this is speculative as we are not yet seeing people move across in relation to Aleppo," Adrian Edwards, UNHCR spokesperson, said.Laerke said about 750 people have been evacuated from Foua and Kefraya, two Shia-majority villages besieged for months by rebel groups.Mohammad Javad Zarif, Iran's foreign minister, said on Tuesday that he hoped a ceasefire agreement could be reached for Syria.Speaking at a meeting with his Russian and Turkish counterparts in Moscow, Zarif said there was no military solution for the Syrian conflict, only a political one.Syria's conflict started as a largely unarmed uprising against President Bashar Assad's rule in March 2011, but it quickly turned into a full-scale civil war that has killed hundreds of thousands.Attempts to negotiate a lasting ceasefire have failed time and again.