The United Nations refugee agency says the number of Syrians fleeing to Jordan has doubled in recent days, with 10,200 arriving in the past week, signaling what could be an impending mass movement.

Spokeswoman Melissa Fleming for the U.N. High Commissioner for Refugees in Geneva says the new arrivals at the Za'atri camp in northern Jordan are mainly from Syria's southern flashpoint area of Daraa. She said refugees reported “being bombed as they were trying to cross” the border.

She said more than 22,000 Syrians have taken shelter at the Za'atri camp since it opened on July 30.

UNHCR representatives also say up to 200,000 Syrian refugees could flee to Turkey if the conflict continues to deepen. They say more than 74,000 Syrians have registered in Turkey, which is building at least five new refugee camps in addition to the existing nine.

More than 3,000 refugees fled Syria to Turkey in the past 24 hours alone.

Meanwhile, The Associated Press reported that Syrian military helicopters dropped thousands of leaflets over Damascus and its suburbs Tuesday, urging rebels to hand over their weapons or be killed.

The AP said some of the leaflets read “The Syrian army is determined to cleanse every inch in Syria and you have only two choices: abandon your weapons … or face inevitable death.''

Syrian authorities blame the 17-month uprising on a foreign conspiracy and accuse oil-rich Gulf countries Saudi Arabia and Qatar, in addition to the United States and Turkey, of backing “terrorists” seeking to oust the government.

On Monday, Syrian rebels said they shot down a military helicopter during heavy fighting with government forces in Damascus.

Amateur video posted online showed what activists claim is a government helicopter falling to the ground in a ball of fire and crashing in a plume of black smoke. The video has not been independently verified.

Syrian state television confirmed that a government helicopter went down in the capital, but did not offer further details.

Activists blame the government for killing hundreds of people several days ago in Daraya, on the outskirts of Damascus. The government says it was battling to crush insurgents based there, while activists say the victims died in shelling or when troops allegedly went house-to-house executing people.