The heads of the UN and European Union aid agencies called on Wednesday (18 December) for a "humanitarian ceasefire" in Syria to allow convoys to deliver help to areas that aid workers cannot reach.
The officials urged all sides in the Syrian war to allow free access for humanitarian groups, saying aid should not be held hostage to political or military considerations.
Calling the Syria conflict the "greatest humanitarian tragedy of our times", the aid chiefs said they feared the worst as another harsh winter threatened even greater suffering.
The statement was issued by UN emergency relief coordinator Valerie Amos, UN High Commissioner for Refugees Antonio Guterres and the heads of the UN Children's Fund, Anthony Lake, and World Food Programme (WFP), Ertharin Cousin, with EU humanitarian aid chief Kristalina Georgieva.
The UN leaders were in Brussels to sign contracts which committed the European Commission to provide €147 million in aid to people affected by the Syrian crisis.
Aid workers have regularly complained that restrictions have been placed on their movement in Syria, particularly by the government of Syrian President Bashar al-Assad.
Blockades have been used mostly by the government but also on a smaller scale by rebels to prevent food and medicine entering besieged areas.
"A humanitarian ceasefire would allow aid convoys to deliver assistance to communities which remain out of our reach," the statement by the UN and EU leaders said, without specifying whether they wanted a national or a local ceasefire.
Some 9.3 million Syrians needed help, the number of internally displaced had grown to 6.5 million and more than 2.2 million refugees had fled the country, the statement said.
The United Nations appealed this week for a record $6.5 billion (€4.6 bn) for Syria and its neighbours to help 16 million people, many of them hungry or homeless victims of a conflict that has lasted 33 months.
The European Commission and the EU's 28 member states have donated more than two billion euros since the start of the Syria crisis, making it the biggest donor, the EU said.
WFP Executive Director Cousin said the humanitarian situation in Syria continued to worsen.
Access problems limited the organisation's ability to reach people in need in many areas of Syria, including in both government and opposition-held zones, she told Reuters in an interview.
"The primary challenge is the areas where there is ongoing conflict ... There is blame that you can place on both sides of this conflict," she said.
"We work to be as innovative as possible, to find roads that one day may be inaccessible because they are besieged ... but the next day we can access it, so we are doing everything possible to reach as many people as possible," she said.
European Commission President José Manuel Barroso said: "The conflict in Syria has consumed tens of thousands of lives, uprooted millions from their homes, destabilised the region and consigned an entire generation of the young to an uncertain future. It is right that we stand up for the victims of this catastrophe, which is why I am proud that today we are signing some of the largest humanitarian contracts ever concluded with trusted humanitarian partners. I urge the international community to follow suit and replicate our gesture of solidarity."
European Commissioner for Humanitarian Aid Kristalina Georgieva said: "Our collaboration with the major UN agencies is vital to the overall relief assistance being provided by Europe for this terrible crisis. Working together has enabled us to reach many of the millions of men, women and children who are suffering as a result of this tragic conflict." "These latest contracts will help us to reach even more vulnerable Syrians and those in the host communities beyond Syria's borders who are struggling under the burden of their generous hospitality.