AMMAN: Around 1,000 Syrians who sought refuge in Jordan have been returning home each month since July when a ceasefire in southern Syria took force, the UN said Monday.

The ceasefire brokered by Jordan, Russia and the United States for the southern Syrian provinces of Daraa, Quneitra and Suweida has largely held since it came into force on July 9.

Since then "the number of Syrians returning to the country voluntarily has increased", Mohammed al-Hiwari, spokesman for the UN refugee agency (UNHCR) in Amman, told AFP.

"Today that number has risen to around 1,000 (returnee) per month on average," Hiwari added.

Jordan shares a border of more than 370 kilometres with Syria, where upwards of 340,000 people have been killed and millions displaced since its conflict broke out in 2011.

The United Nations says Jordan is hosting more than 650,000 Syrian refugees, but authorities in the kingdom put their actual number at 1.3 million.

Hosting the refugees has placed a heavy burden on Jordan, a country lacking natural resources.

According to Hiwari, the number of refugees who returned voluntarily to Syria rose to 1,203 in August and 1,078 in September.

In the six months before the ceasefire, a total of only 1,700 Syrian refugees returned to their home country, he said.

Hiwari stressed that the UNHCR "does not encourage the return to zones in Syria that are deemed unsafe".

The ceasefire brokered in the three southern Syrian provinces is part of a broader Russian-backed plan to create four "de-escalation zones" in rebel-held parts of the country.

Russia and Iran, main allies of the Syrian government, and rebel-backer Turkey agreed in May to create the four zones in a deal aimed at bringing about a lasting truce.