UN agency heads stressed on Tuesday there was "no humanitarian solution" to the Syrian conflict although the world body would do its best to help those in need, following a mission to the war-torn country.

"The plight of Syrian people is appalling, but it is exactly what you would expect after two years of unrelenting conflict. So many have died, so many have been injured, so many have had their lives destroyed. It stands out for us that Syrians are destroying their own country," said mission leader John Ging.

Ging, head of operations for the UN Office for the Coordination of Humanitarian Affairs (OCHA), said: "This is a political problem. There is no humanitarian solution to the conflict.”

"The humanitarian organisations must do what we can to help people survive this. But our first appeal is to the political leadership of this world."

"If you doubt the scale of the travesty, then you should come and visit and see for yourselves. Answer to the mothers and fathers and children there who see no hope on the horizon ... you should answer to them for the political failure because they are bearing the consequences."

During their four-day mission, representatives from the World Food Programme, the UN refugee agency and others traveled to the southern province of Daraa, the embattled outskirts of Damascus and across the front line in the central city of Homs.

"Our mission crossed the conflict line yesterday. We had to negotiate with the government and with the opposition leadership, and the good news is that both sides were committed to the transmittal of humanitarian aid wherever it was needed," said Ging.

"There was in fact an agreement to cease fire during the period of our mission ... If it can be done for four hours of our mission, why can't it be extended for the Syrian people by the leaderships on both sides?" he asked.

"We visited hospitals that were without basic supplies," the official said adding that "wanton destruction is taking down this country, the capacity to deliver services, the electricity network, the water network."

He responded to a demand by the opposition Syrian National Coalition that the world body cease to distribute any aid through government institutions, saying:

"The aid effort led by the UN in Syria is directed through humanitarian partners, NGOs and community-based organisations. We do not donate to the government of Syria. Full stop."

The OCHA representative called on the international community to step up its funding for the UN mission, which is seeking to help fulfill a $519 million target at an upcoming donor conference in Kuwait.