UN humanitarian affairs and emergency relief co-ordinator Valerie Amos told reporters that the violence in Syria "has become more intense and is too often indiscriminate."
"Back in March, we estimated that a million people were in need of help," Amos said Thursday. "Now as many as 2.5 million are in need of assistance and we are working to update our plans and funding requirements."
She urged all parties to do more to protect civilians and said she is lobbying the government to be "more flexible in its approach to humanitarian operations."
"There are eight international NGOs (non-governmental organizations) currently operating in the country and we have the agreement of the government that they can supply humanitarian assistance," she said.
"They have put together projects which they have submitted to [the Syrian Arab Red Crescent]. Once those are agreed we can start implementation and implementation has already started in some areas. What I would like to see is the government extending that facility to other large NGOs from the international community who we know can really help to scale up the efforts significantly. I have not been able to get that agreed."
Amos, who has been in Syria since Tuesday, visited displaced families in Damascus and An Nabk. She said they were "tired and anxious" and didn't expect to be able to safely return home soon.
The UN is able to meet some needs, but many people are beyond reach because of the security situation. Funding is also an issue, and Amos called on international donors to contribute more.
On Wednesday, Foreign Affairs Minister John Baird said that Canada has changed course and will not move forward with a plan to give $2 million to a Syrian-Canadian group for medical supplies. The foreign affairs department has been in touch with allies to find other ways to get medical supplies to Syrians, Baird said.
The fighting has prompted thousands of people to flee to neighbouring countries, including Jordan, Lebanon and Turkey. As of August 13, there were 157,577 refugees who are formally registered or in the process of being registered in surrounding countries, the UN said. That number does not reflect the people who stream across the border and choose not to register.
In recent days, President Bashar al-Assad's fighters and rebels have been clashing in and around Aleppo, a commercial hub in the country's north. Syrian government airstrikes on a residential neighbourhood in a rebel-held town killed over 40 people and wounded at least 100 others including many women and children, international watchdog Human Rights Watch said Thursday.
The strikes on the town of Azaz in northern Syria a day earlier levelled much of a poor neighbourhood and sent panicked civilians fleeing for cover. So many were wounded that the local hospital locked its doors, directing residents to drive to the nearby Turkish border so the injured could be treated on the other side.
Also on Thursday, state-run television said government troops freed three journalists who were seized last week by rebels while covering violence in a Damascus suburb.
UN considers new Syria office
The news of the ever-worsening humanitarian situation in Syria comes as the UN struggles to work out what will happen when the mandate for the UN observer mission in Syria lapses.
The Security Council on Thursday will debate whether to establish a new civilian office to support UN and Arab League efforts to end the 18-month conflict in Syria as the UN military observer mission comes to an end Sunday.
The council had set two conditions for possibly extending the mission of the unarmed observers past Aug. 19: a halt to the government's use of heavy weapons and a significant reduction in violence. In a letter to the council last Friday, UN Secretary-General Ban Ki-moon said neither condition was met and Syria now risks "a descent into a full-scale civil war."
Ban has said that it is "imperative" for the UN to have a presence in Syria beyond its humanitarian operation so it can support UN-Arab League efforts "in mediating and facilitating peaceful resolution to the crisis."
"I intend therefore to work in the immediate future towards establishing an effective and flexible United Nations presence in Syria that will support our efforts with the parties to end hostilities," Ban said.
The observer mission has not been without problems — observers struggled to gain access to many parts of the country amid security concerns and escalating violence. In July, half of the 300 observers in Syria were sent home, though UN officials noted they could be recalled if the circumstances in the country changed.
According to a Reuters report, the U.S. envoy to the UN Susan Rice has previously said the monitoring mission shouldn't be extended because there is no ceasefire for the observers to monitor.