UN Secretary General Ban Ki-moon says that half of Syria’s population, some 9.3 million people, now “urgently need humanitarian aid”.
He was speaking at a donor conference in Kuwait launching the UN’s biggest ever appeal for a single crisis.
The UN is seeking $6.5bn (£4bn) – it raised $2.4bn by the end of Wednesday.
Meanwhile, Syria’s deputy foreign minister has said Western intelligence agencies have held talks with Damascus on combating Islamist groups in Syria.
The growing influence of such groups among rebels fighting President Bashar al-Assad has complicated the conflict and caused international concern.
The UK government denied having any such co-operation with Damascus.
BBC