Jordan is also refusing to take any more refugees as Assad regime hits rebel-held areas in Syria’s south-west

Israel has deployed artillery and armoured reinforcements along its northern border with Syria, the Israel Defence Forces said on Sunday, as tens of thousands of Syrians fled towards its borders and those of Jordan.

Russian efforts to impose a broad ceasefire in south-west Syria broke down at the weekend, prompting the Syrian regime to undertake fresh air raids. The government forces now claim to be in control of more than half of Daraa province.

The fighting is in a diplomatically delicate region, abutting both Jordan and the Israel-occupied Golan Heights. As many as 11,000 refugees had already reached the Israeli border fence on the Golan Heights on Sunday, judging it the safest place to avoid Syrian air force raids. Some of the refugees were asking Israel to protect them or even annex the territory.

The Israeli prime minister, Benjamin Netanyahu, discussed the humanitarian crisis in Syria during a Sunday government meeting, saying: “We will continue defending our borders, we will provide humanitarian aid as best as we can, we will not allow entry to our territories and demand strict adherence to the 1974 Agreement on Disengagement with the Syrian army.” He said he was in touch with the White House.

Facebook Twitter Pinterest Jordanian soldiers at the border with Syria, where thousands have fled to escape the airstrikes. Photograph: Anadolu Agency/Getty Images

Neighbouring Jordan says it cannot afford to take any more refugees and is turning away the internally displaced at the border.

For the Syrian president, Bashar al-Assad, the retaking the whole of Daraa province would be a key symbolic victory for the regime, as it is seen as the cradle of the anti-Assad uprising seven years ago that spiralled into civil war.

But just under half of Daraa province – including part of the provincial capital of the same name – still remains in the hands of rebels, and the UN is putting the numbers of internally displaced at over 160,000. The fighting in the Daraa province going on even though the territory is inside the de-escalation zone agreed last year by the US president, Donald Trump, the Russian president, Vladimir Putin, and the Jordanian government.

Syrian rebel spokesman Ibrahim Jabawi, rejecting the Russian terms for a deal, said: “The talks collapsed because the Russians insisted on their conditions that want us to surrender.” He said Russia wanted the rebels to hand over their weapons followed by a return of government forces to rebel-held areas.

A negotiator in the rebel-held part of Daraa city told Agence France-Presse: “All people who carried arms would be put on trial. The regime wants us to hand over everything – Daraa city, the Nasib crossing, ourselves and the heavy weapons. It’s inadmissible.”

Syrian’s main opposition group, the Syrian Negotiation Commission (SNC), implored the international community to speak out against the violence, saying it should be clear to members of the UN security council that Russia and Iran “cannot be trusted to negotiate peace, since they are violating the agreement they themselves made”.

“We call on the international community to condemn the brutal breaching of the de-escalation zone ... and take all possible measures to halt this assault on our people,” SNC spokesman Yahya al-Aridi said.

Facebook Twitter Pinterest A rebel-held town east of the city of Daraa during airstrikes on Saturday. Photograph: Mohamad Abazeed/AFP/Getty Images

It is estimated that as many as 115 civilians have been killed in regime bombardments on the province since 19 June.

Aa many as 20,000 refugees are close to areas near the Nasib border crossing with Jordan, a country that already hosts more than 650,000 registered Syrian refugees and says the actual figure is closer to 1.3 million.

Amman says it cannot open its frontier to any more Syrians fleeing the seven-year conflict, but on Saturday announced it had sent aid across the border to the displaced.

Pope Francis has decried the intensified attacks in southern Syria, asking that people there be spared more suffering.

In remarks at the Vatican, he said “the military actions of recent days have struck even schools and hospitals and triggered thousands of new refugees.”