AMMAN — An alleged chemical weapons attack by Syrian regime forces near Damascus drove thousands of displaced Syrians towards Jordan on Wednesday in what activists are calling the largest refugee migration since the onset of the conflict two years ago.

Border region residents in Syria and rebel officials said thousands of their compatriots fled their homes on Wednesday following a purported chemical weapons attack in the towns of Ghouta Sharqiyya and Ghouta Gharbiyyah outside Damascus.

Agence France-Presse quoted the opposition as saying that a chemical attack by the Syrian regime killed over 1,300 people.

The agency said the claim could not be independently verified, adding that it was vehemently denied by the Syrian regime, which said it was intended to hinder the mission of UN chemical weapons inspectors now in the country.

The Local Coordination Committees (LCC), a network of activists, reported hundreds of casualties in the “brutal use of toxic gas by the criminal regime”, AFP reported.

“After today’s massacre, entire villages have been evacuated and all are heading to southern Syria and Jordan,” said Abu George Al Jolani, commander of a Free Syrian Army battalion stationed near Ghouta Gharbiyyeh during the reported chemical weapons attack.

“Old men, women, children — anyone who can still walk is heading towards Jordan,” he claimed.

“Anyone who remains may be as good as dead.”

According to activists, some 10,000 civilians fled from the Damascus governorate and headed towards southern Syria late Wednesday, with border towns and villages reportedly receiving “mass waves” of hundreds of displaced families.

“Families from Ghouta are arriving by the hundreds and filling the streets” said Ahmad Al Saad, activist with the LCC in the border town of Tal Shihab, which reportedly received over 1,000 displaced people as of late Wednesday.

Rebel forces claimed that regime forces deployed sarin gas on the outskirts of the town of Shaikh Al Maskin near Daraa early Monday, an incident that spurred a separate refugee exodus towards Jordan.

Meanwhile, border violence continued to reduce the Syrian refugee influx into Jordan to a trickle, with the Jordan Armed Forces reporting some 90 Syrians crossing into Jordan.

Jordan has opened its borders to over 560,000 Syrians since the onset of the conflict in March 2011.