A report from children's charity World Vision and Frontier Economics has shown billions of pounds are lost each month in economic growth.
Chris Weeks from World Vision, who was in Lebanon last month, told Premier it is not just about money.
He said: "If you go into a refugee camp, say in Jordan, and you just go down one row and you speak to these families, you'll hear untold stories of misery and devastation - of children just trying to get on with their lives, trying to study, but their school was blown up by a tank - there was sniper fire in the street."
The charity is now urging the UK government to lead a reconstruction plan for Syria, which will be 'ready to go' when the war ends.
Chris Weeks continued: "Syria can't rebuild itself on its own - it's Syrians who should dictate what happens to their country, but this is now a global problem. It's going to need a global response and we need Britain to rally world leaders to get together to offer that support for Syria."
He said that people want to return to their once-prosperous country: "People are still really, painfully close to the towns and cities they come from, just across the border.
"And they just want to return. When you ask them what life was like, they speak in glowing terms of a great life over there and we say lives have been destroyed. We're not just talking about infrastructure and schools too."
Listen to Premier's Aaron James speak to Chris Weeks from World Vision here:
