Turkish President Recep Tayyip Erdogan has vowed to expand Ankara’s operation in a Kurdish enclave in northern Syria towards the border with Iraq.

In Vienna, the Syrian opposition and Russia agreed to a ceasefire to halt the fighting over the besieged eastern Ghouta suburbs of Damascus, an area the UN has called the “epicentre of suffering” in the war-torn country.

The agreement, confirmed to The Associated Press by opposition official Ahmad Ramadan, is contingent on Russia compelling the government to allow aid flow to the suburbs, according to the Syrian Observatory for Human Rights monitoring group.

Russia is a key ally of Syrian President Bashar Assad.

Turkey SyriaMr Erdogan said the Turkish forces’ offensive will continue ‘until no terrorist is left’ (Yasin Bulbul/Pool Photo via AP)

Rebels gave the government 24 hours to comply, said Ammar Hassan, spokesman for the Islam Army, one of the factions fighting inside the area.

The government did not sign the agreement, said opposition adviser Omar Kouch.

The eastern Ghouta area has seen more than two months of violent fighting since rebels tried to ease a choking government blockade that has depleted food and medical supplies.

The UN reported in November that child malnutrition in eastern Ghouta was at the worst ever recorded throughout the seven years of civil war.

It estimates there are around 400,000 people trapped under the government’s siege.

Conditions deteriorated precipitously after pro-government forces choked off the last smuggling tunnels leading to the opposition-held suburbs in May.

A “de-escalation” agreement brokered by Russia, Iran, and Turkey in August failed to bring any relief.

The government and rebels eased up on their fighting but the government refused to allow aid into eastern Ghouta contravening the agreement.

Fighting erupted again in November, leading the government to pound the enclave with airstrikes and artillery fire without distinguishing between civilian and military targets.

Rebels have responded with waves of shelling on Damascus.

At least 286 civilians have been killed in the crossfire in the last month alone, according to figures from the Observatory.

UN envoy Staffan de Mistura, third right, and Syrian chief negotiator and Ambassador of the Permanent Representative Mission of Syria to the United Nations Bashar al-Jaafari, second left, sit with other delegate members ahead of the start of official talks on Syria, in Vienna (Alex Halada/pool via AP)UN envoy Staffan de Mistura, third right, and Syrian chief negotiator and Ambassador of the Permanent Representative Mission of Syria to the United Nations Bashar al-Jaafari, second left, sit with other delegate members ahead of the start of official talks on Syria, in Vienna (Alex Halada/pool via AP)

The agreement, the latest in a long line of short-lived truces for Syria, was announced on the second and last day of a UN-mediated round of peace talks in the Austrian capital.

Another round, mediated by Russia, starts in Sochi on Monday.

Mr Erdogan said the Turkish forces’ push into Afrin would stretch further east, to the Syrian Kurdish town of Manbij, and towards the border with Iraq “until no terrorist is left”.

His latest comments appeared to be in defiance of the United States, which has urged Turkey to keep its campaign in Syria “limited in scope and duration” and to focus on ending the war.

Turkey considers the Syrian Kurdish forces, known as the People’s Protection Units, or YPG, to be a terrorist group because of their purported links to Kurdish insurgents within Turkey’s own border.

Manbij is held by the Syrian Democratic Forces, which is dominated by the YPG.

“We will clear Manbij of terrorists… No one should be disturbed by this because the real owners of Manbij are not these terrorists, they are our Arab brothers,” Mr Erdogan said.

“From Manbij, we will continue our struggle up to the border with Iraq, until no terrorist is left.”

Mr Erdogan’s remarks came on the seventh day of the Turkish incursion into Afrin, which started last Saturday.