"The Syrian crisis has become the biggest humanitarian emergency of our era, yet the world is failing to meet the needs of refugees and the countries hosting them," Antonio Guterres, UN High Commissioner for Refugees, said in a statement.
According to the figures by United Nations, three million Syrian refugees will have registered in neighbouring countries as of Friday. The figure is one million refugees more than a year ago.
The vast majority remain in neighbouring countries, with the highest concentrations in Lebanon (1.14 million), Turkey (815,000) and Jordan (608,000), the UNHCR said. Some 215,000 refugees are in Iraq with the rest in Egypt and other countries.
In addition, the host governments estimate that hundreds of thousands more Syrians have sought sanctuary in their countries without formally registering, the agency said.
Increasing numbers of families arrive in a shocking state, exhausted, scared and with their savings depleted, it said. "Most have been on the run for a year or more, fleeing from village to village before taking the final decision to leave."
"There are worrying signs too that the journey out of Syria is becoming tougher, with many people forced to pay bribes at armed checkpoints proliferating along the borders.
Refugees crossing the desert into eastern Jordan are being forced to pay smugglers hefty sums (ranging from $100 per person or more) to take them to safety," it added.