UN refugee chief Antonio Guterres said Friday it was vital that peace talks next week on the Syrian civil war find a "political solution" to the conflict.
And he issued a fresh appeal for the world to help ease the massive burden on countries which have taken in millions of Syrian refugees.
"I am humble enough to recognise that there is no humanitarian solution for this problem. The solution is political," he told a meeting in Turkey of regional refugee-hosting nations.
"That's why it is very important to send a clear message to the international community gathering in Geneva next week that it is absolutely central to stop this bloodshed and to find a political solution," he said.
Friday's meeting in the Harran refugee camp on the border with Syria brought together officials from Egypt, Iraq, Jordan and Lebanon to discuss humanitarian aid efforts for the massive tide of Syrians who have fled their homeland.
It comes five days before the Geneva II peace conference aimed at finding an end to the 34-month conflict that has claimed more than 130,000 lives and displaced millions of people.
"What Syrian people need is peace and the possibility to go back to their country and to rebuild their country," said Guterres.
"Just six years ago Syria was the second largest refugee-hosting country in the world, with more than two million refugees... unfortunately today Syria is the fastest producing refugee country in the world".
He said host countries needed "massive financial support" to address the challenge and made an appeal to all countries in the world to share the burden.
"This is a responsibility of the international community. That's why we are strongly appealing for all borders everywhere to be opened to Syrians, not only the borders of the neighbouring countries.
"For me it is unacceptable to see Syrian refugees drowning, dying in the Mediterranean or pushed back at some borders," he said.
The United Nations this week launched an appeal for $6.5 billion in what it said was the largest ever in its history for a single humanitarian emergency.
A donors' meeting in Kuwait on Wednesday pledged more than $2.4 billion for victims of the Syrian war, less than half the amount sought.