Syrian president Bashar al-Assad has vowed to use military force to regain control of the north of the country if rebels refuse to surrender and bring an end to the seven-year civil war.

“We have chosen two paths,” Mr al-Assad said in an interview with Russian television channel NTV on Sunday. “The first and most important one is reconciliation. The second path is to attack terrorists if they don’t surrender and refuse to make peace.”

Asked about the rebels in the north of the country where groups backed by Turkey hold territory, he said: “We will fight with them and return control by force. It is certainly not the best option for us, but it’s the only way to get control of the country.”

The president’s warning came as government forces continued their offensive in the south western of Syria near the borders with Jordan and the Israeli-occupied Golan Heights.

On Saturday night Russian jets provided support,launching at least 20 airstrikes on the rebel-held town of Busra al Harir, according to rebels and residents.

Iranian-backed fighters are also believed to be supporting the Syrian army’s offensive against a string of rebel held towns in Quneitra province near the Israeli border.

On Sunday Israel’s military said it had launched missiles at an incoming drone from Syria, forcing it to turn away from the border.

The US has previously threatened to take “firm and appropriate measures” if the Syrian government and Russia violated the “de-escalation zones” agreed last year.

However it has since emerged it has also told the Free Syrian Army group not to expect military support.

In a message sent to the rebel leaders, the US warned: “You should not base your decisions on the assumption or expectation of a military intervention by us.”

"War of Annihilation" – devastating toll on civilians in Raqqa, Syria Show all 20 1 /20 "War of Annihilation" – devastating toll on civilians in Raqqa, Syria "War of Annihilation" – devastating toll on civilians in Raqqa, Syria A child injured by an IED explosion in Raqqa Amnesty International "War of Annihilation" – devastating toll on civilians in Raqqa, Syria Children riding a bicycle among destroyed buildings in Raqqa Amnesty International "War of Annihilation" – devastating toll on civilians in Raqqa, Syria Entire neighbourhoods in Raqqa are damaged beyond repair Amnesty International "War of Annihilation" – devastating toll on civilians in Raqqa, Syria Satellite image showing the house where seven members of the Badran family were killed in a Coalition strike on 18 July 2017, before the strike CNES/Airbus DS "War of Annihilation" – devastating toll on civilians in Raqqa, Syria Satellite image showing the house where seven members of the Badran family were killed in a Coalition strike on 18 July 2017, after the strike CNES/Airbus DS "War of Annihilation" – devastating toll on civilians in Raqqa, Syria Members of the Badran family killed in three separate Coalition air strike on 18 July and 20 August 2017 in Raqqa Amnesty International "War of Annihilation" – devastating toll on civilians in Raqqa, Syria The city of Raqqa in northern Syria has become hardly recognizable to those who try to return after months battle between US-backed forces and the Islamic State terrorist group for control of it. The city has no running water or electricity and homes, business and public squares are mere rubble and debris Amnesty International "War of Annihilation" – devastating toll on civilians in Raqqa, Syria Satellite image showing the houses where 16 members of the Fayad family and neighbours were killed in Coalition strikes on 12 October 2017, before the strike CNES/Airbus DS "War of Annihilation" – devastating toll on civilians in Raqqa, Syria Satellite image showing the houses where 16 members of the Fayad family and neighbours were killed in Coalition strikes on 12 October 2017, after the strike CNES/Airbus DS "War of Annihilation" – devastating toll on civilians in Raqqa, Syria Fayad Mohammed and his daughters Wafa’, Fadda and Tamam; Ammar al-Faris; Reem al-Maddad, Yusra Abd-al-Aziz, and baby Razqiya Habib; Jasim Hamal and Salem Hamad. They were among the 16 civilians killed in Coalition air strikes on 12 October 2017 in Raqqa Amnesty International "War of Annihilation" – devastating toll on civilians in Raqqa, Syria Men wait by the side of the road for casual labour in Raqqa. Many end up clearing partially destroyed or damaged buildings, a very risky endeavour as many building were mined by IS and civilians are frequently killed and injured by mines Amnesty "War of Annihilation" – devastating toll on civilians in Raqqa, Syria Satellite images showing the Aswad family’s building before it was destroyed in a Coalition air strike which killed eight civilians, five of them children, on 28 June 2017 CNES/Airbus DS "War of Annihilation" – devastating toll on civilians in Raqqa, Syria Satellite image showing the Aswad family’s building after it was destroyed in a Coalition air strike which killed eight civilians, five of them children, on 28 June 2017 CNES/Airbus DS "War of Annihilation" – devastating toll on civilians in Raqqa, Syria Amal Othman, 13, and her brothers Ammar, 8 and Mahmoud, 17; and Jamal Aswad, 41 – four of the eight victims killed in a Coalition air strike on 28 June 2017 in Raqqa Amnesty International "War of Annihilation" – devastating toll on civilians in Raqqa, Syria Low-income district west of the Jezra intersection on the western outskirts of Raqqa city destroyed by the Coalition shelling started in June 2017 Amnesty International "War of Annihilation" – devastating toll on civilians in Raqqa, Syria Satellite image showing the houses where 16 members of the Fayad family and neighbours were killed in Coalition strikes on 12 October 2017, before the strike CNES/Airbus DS "War of Annihilation" – devastating toll on civilians in Raqqa, Syria Satellite image showing the houses where 16 members of the Fayad family and neighbours were killed in Coalition strikes on 12 October 2017, after the strike CNES/Airbus DS "War of Annihilation" – devastating toll on civilians in Raqqa, Syria Ali Hassan Nafa; Mahdia Hashish and her husband Hussein Ali; Hussein Hashish, Mohammed Hashish and Hussein Ibrahim Hashish, and Mohammed Ali Hashish Amnesty International "War of Annihilation" – devastating toll on civilians in Raqqa, Syria Harat al Badu, a built up area in central Raqqa, next to the stadium. It was the scene of the final battle in the city between SDF/Coalition forces and IS Amnesty International "War of Annihilation" – devastating toll on civilians in Raqqa, Syria Map showing where the Badran, Hashish, Aswad and Fayab families were living before the coalition air strikes Unosat /Amnesty International

“We in the United States government understand the difficult conditions you are facing and still advise the Russians and the Syrian regime not to undertake a military measure that violates the zone,” the message added.

The US has supported the FSA with millions of dollars worth of arms during the civil war as part of an aid programme run by the CIA.

Mr al-Assad also told Russian TV that Syria would not accept any Western money to help rebuild the country.

“We have enough strength to rebuild the country. If we don’t have money – we will borrow from our friends, from Syrians living abroad,” the president said.