Beirut - Fighters battling a fierce government-led offensive in southern Syria have reached an agreement with Russia, a major ally of Syrian President Bashar al-Assad, to end violence in the area and surrender a key crossing point with Jordan, according to a rebel spokesman.

Ibrahim Jabawi, spokesman for the rebels' joint operations room, was quoted as saying by news agencies that under Friday's agreement reached  with Russian negotiators the fighters will begin to hand over some of their heavy weapons in return for a government pullout from several villages.

Jabawi added that Russian military police will deploy along the border with Jordan, including the strategically important Naseeb border crossing, and that rebels opposed to the deal will be evacuated to rebel-held regions in northern Syria.

There was no immediate comment from Assad's government and its Russian backers.

Shortly afterwards, an Al Jazeera reporter on the ground saw a convoy of about 10 army trucks with Russian and Syrian flags entering the strategically important Nassib border crossing, held by the rebels for three years. Another seven trucks were waiting to enter.

Taking over Nassib crossing would allow the Syrian army to drive further southwards through the area immediately east of Deraa city, where rebel territory narrows to a thin corridor along the Jordanian border. This would split the territory in two.

Russia has been brokering talks for the surrender of rebel-held territory in southern Syria, in areas bordering Jordan and the Israeli-occupied Golan Heights.

According to rebels, Moscow had previously rejected their demands for a phased surrender of their heavy-duty arms and safe passage for rebels and civilians who did not want to live under government rule to opposition territory elsewhere.

More than 320,000 people have fled the intense fighting and bombardment since the launch of the government-led push on June 19, according to the UN's refugee agency, UNHCR.

About 60,000 have gathered at the Nassib-Jaber border crossing overlooking Jordan, while thousands more are at the frontier with the Israeli-occupied Golan heights.

Friday's agreement came a day after Jordan, which hosts more than 1.4 million Syrian refugees and has shut its northern border, said it had managed to convince the Syrian opposition and the Russians to meet again and reach an agreement for a cessation of hostilities.

But the announcement only came after government forces advanced earlier on Friday along the frontier with Jordan towards the Nasib border crossing, sources on the ground said.

Commenting on the negotiations, Jumana Ghunaimat, spokeswoman for the Jordanian government, told Al Jazeera: "The solution in Syria is political, not military. The war and more fighting won't stop the struggles of the Syrian people."

Ghunaimat added: "We need to stop the war, and that is the main goal of negotiations which we are mediating."

Haid Haid, a Syrian columnist and a consulting research fellow at Chatham House, called the gradual withdrawal of rebels and the handing over of the weapons a "big gain" for Assad's government.

"It doesn't only allow it to extend its authority over a big chunk of rebel controlled areas, but it also allows it to control the main border with Jordan, which will restore some sort of relation with Jordan and allow the regime to generate financial revenues from the trade that will expected to go through that venue," he told Al Jazeera from Britain's capital, London.

Haid added, however, that there was a still a lack of clarity about the exact details included in the agreement.

"We need to wait until the conditions of that deal are out and clear, because some of the conditions are related to what will happen to rebel forces who stay in those areas - will they will be able to have some kind of control over their territories … or will the regime be able to take over full control over those areas and push them out of any local authority?

"Another issue that is still not clear is what will happen to many of the rebel forces who decided stay there, because there is only a small part of them who will go to northern Syria, while the majority of them will stay there - will they automatically become regime forces, or will they have some sort of special status?"