US Secretary of State John Kerry on Thursday visited Jordan's sprawling Zaatari camp, home to tens of thousands of Syrian refugees, to see first hand the resulting tragedy of the Syria conflict.

Kerry first overflew the vast camp by helicopter, surveying hundreds of tents and trailers lined up on desert sands about 20 kilometres (12.4 miles) from the Syrian border.

Kerry said his visit had "put a real human face" on the situation, describing his conversations with refugees and officials at the camp as "searing and unforgettable."

He met with six refugees, two men and four women, for 40 minutes. They expressed anger and repeatedly asked Kerry to establish buffer and no-fly zones in Syria.

"Where is the international community? What are you waiting for? We hope that you will not go back to the United States before you find a solution to the crisis. At least impose a no-fly zone or an embargo," said a refugee woman who did not give her name.

The refugees also urged the international community to help put a halt to the flow of weapons from Iran and influx of Lebanese Hizbullah fighters into Syria.