A child stands next to rebel soldiers outside Aleppo
The new UN and Arab League envoy for Syria has said the death toll in the conflict is "staggering" and the destruction "catastrophic".
Speaking to the UN General Assembly in his first formal speech since assuming the role, Lakhdar Brahimi called for unity in addressing the crisis, reports the BBC.
He said he would travel to Syria in the next few days and needed UN support.
Syria's UN ambassador said Damascus was ready to co-operate with Brahimi's mission.
In his brief statement, Brahimi told the assembly in New York that the situation in Syria was deteriorating, and that "the suffering of the people is immense".
He said the future of Syria would be "built by its people and none other", and that "the support of the international community is indispensable and very urgent".
"It will only be effective if all pull in the same direction," he said.
Brahimi was appointed last month, after his predecessor, Kofi Annan, resigned following the failure of his peace plan.
The UN's Secretary General Ban Ki-moon said his mission was "daunting, but not insurmountable" and called for "a unity of effort that will have an impact on the ground".
He told the assembly the conflict had "taken a particularly brutal turn" and that the increasing militarisation was "deeply tragic and highly dangerous".
But UN efforts to relieve the growing humanitarian crisis were being hampered by a lack of funding, with a $180bn (£113bn) plan only half funded, he said.
Ban accused countries who sent arms to Syria of spreading misery. He did not name any country, but Russia is Syrian President Bashar al-Assad's main arms supplier.
Earlier on Tuesday, UN High Commission for Refugees (UNHCR), said the total number of refugees from Syria who have either been registered or are awaiting registration now stands at 235,300, with 103,416 people seeking asylum in August alone.
High Commissioner Antonio Guterres said the numbers - and particularly the rapid escalation during August - are worrying.
The increase is placing huge pressure on the host countries, he told the BBC, which have "accepted everybody asking for protection".
"But they need the support of the international community, and my appeal is for that international community not to leave these countries alone in the huge effort to provide protection and assistance to the Syrians fleeing their country."
The head of the International Committee of the Red Cross, Peter Maurer, held a brief meeting with Syrian President Bashar al-Assad on Tuesday, which the ICRC described as "positive".
The ICRC said Maurer had called on Assad to allow greater access for humanitarian workers.
Syrian state television said President Assad supported the ICRC's humanitarian work in Syria as long as it remained "independent and impartial".
The Syrian uprising against President Assad began relatively peacefully last year, but has deteriorated in the heavy arms conflict in the streets of many towns and cities.
August was arguably the violent month yet, with the pro-opposition Syrian Observatory for Human Rights reporting more than 5,000 deaths.