In the back of small trucks so crammed that children have to loll on adults' legs, refugees are fleeing war-broken Syria for what they fear will be a long period in camps in neighbouring countries.

Roads leading north, past Idlib and Aleppo to the Turkish border, hold many such vehicles, their occupants gazing listlessly back at the shattered country they are leaving behind.

In one such truck carrying 17 people, the adults said they paid the equivalent of $30 each for the two-hour journey while their children travelled free.

A father who declined to be named said he had been forced to close his small shop in Damascus and make the trip with the other eight members of his family for his childrens' sake.

His eight-year-old daughter suffered tremors every time she heard explosions or aircraft overhead, he explained.

Another passenger, a defected Syrian soldier who gave his first name as Shady, said: "I'm leaving because of shelling, bombardment and aircraft. There is no food and we are such hungry people."

It had been a hard decision to leave, the 22-year-old said, but "the situation is so difficult and tragic" that he had no choice.

He was joining his family who was already in one of the refugee camps in Turkey.

He and others in the truck shrugged when asked how long they thought they would live in Turkey. "I think it will be a long time," said the father.

At the Bab Al-Hawa border crossing, the Syrians showed their identification cards to rebels manning the post who waved them through to join a long line of vehicles barely moving under rain.

A few hundred metres (yards) later, all passengers were told by Turkish border guards to get out and walk the two kilometres (1.2 miles) through the passport control and checkpoints to Turkey. Several struggled with heavy suitcases and small children.

Once to the other side, it was another truck ride to one of the several refugee camps set up: tent cities where blankets and electricity were available -- but monotony and frustrations of living in close quarters reigned.

The UN's refugee agency, UNHCR, says that more than 700,000 Syrian have registered or were waiting to register as refugees in Turkey and other countries around Syria, with their number swelling significantly in the past few weeks.

The outflow has swamped the capacity of the agency and non-governmental organisations.

The United Nations is urgently seeking more funding to cope. UN chief Ban Ki-moon was expected to ask for more than $1.5 billion in new cash pledges at a donors conference in Kuwait on Wednesday.