BEIRUT (Reuters) - Jihadists and other rebel groups made advances against the Syrian army north of Hama on Thursday, a monitor said, part of their biggest offensive for months, underscoring bleak prospects for peace talks that resume later in the day.

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A Syrian military source said the government was summoning reinforcements for a counter-offensive. “We have absorbed the attack and we are consolidating defense lines set up in the areas breached,” he told Reuters.

Since their Hama assault began late on Tuesday, rebels have captured at least 11 villages and towns from the army, the Syrian Observatory for Human Rights, a Britain-based war monitoring group, said.

The assault coincides with clashes in the capital Damascus, where rebels and the army are fighting on the edge of the city center in the Jobar district for a fifth day amid heavy bombardment, state media and the monitor said.

It seems unlikely to reverse 18 months of steady military gains by the government, culminating in December’s capture of the rebel enclave in Aleppo, but it has shown the army’s difficulty in defending many fronts simultaneously.

Increased fighting, despite a ceasefire brokered in December by Russia and Turkey, casts further doubt on peacemaking efforts in Geneva, where talks resume on Thursday after making no progress toward peace in recent rounds.

“We hope to see some serious partners on the other side of the table,” Salem al-Muslet, spokesman for the opposition’s High Negotiating Committee (HNC), said in Geneva.

Syrian President Bashar al-Assad’s government, backed by Russia, Iran and Shi’ite militias, is attending the Geneva talks. Both sides blame each other for violating the ceasefire.

The government accused rebels of launching attacks in an attempt to “impact negotiations in Geneva”, state news agency SANA reported.

Near Hama, rebels spearheaded by the jihadist Tahrir al-Sham alliance, but also including groups fighting under the Free Syrian Army banner, made new gains overnight and fighting continued on Thursday, the Observatory said.

They had so far defeated army forces north of Hama in about 40 positions, including towns, villages and checkpoints, advancing to within a few kilometers of the city and its military airbase, it said. In one area, rebels took the village of Shaizer, nearly encircling the army-held town of Moharada which is inhabited mainly by Christians.

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The Observatory said government forces began counter-attacking along several fronts on Thursday, with intense air strikes pounding the towns of Khattab, al-Majdal and others.

“It’s never good for talks if civilians are suffering on both sides, but it could also be an impetus for progress in talks,” U.N. Syria humanitarian advisor Jan Egeland told Reuters. Peace efforts in Geneva were the “only big hope” for the six-year-old conflict, he added.

HAMA AND DAMASCUS

Tahrir al-Sham’s strongest faction is the former Nusra Front group, al Qaeda’s affiliate in Syria until they broke formal ties last year.

The United States, which has supported some FSA groups during the war along with Turkey and Gulf monarchies, has targeted Tahrir al-Sham leaders with air strikes since January.

Samer Alaiwi, an official from the Jaish al-Nasr FSA group, which is fighting near Hama, said on a rebel social media feed that the offensive was aimed at relieving pressure on rebels elsewhere and stopping warplanes using a nearby airbase.

“After the failure of political conferences and solutions, the military operation is an urgent necessity,” he said.

Save the Children said the escalation in fighting has displaced thousands of families, citing humanitarian staff on the ground. “At least 10,000 people have had to flee their home in the Hama area alone” in recent days, the nonprofit said.

In Damascus, the intensity of clashes around the industrial zone in Jobar increased after midnight, the monitor said.

A military media unit run by the government’s ally Hezbollah and state media reported clashes on Thursday in Jobar and heavy bombardment hitting rebel positions in the area.

State TV showed a reporter speaking in the capital’s Abassiyin district at morning rush hour, but the road appeared quiet with only one or two cars and a few pedestrians, and with the repeated sound of blasts in the background.

Clashes around Damascus have cut 300,000 people off from aid in the besieged rebel-held suburbs east of the capital, Egeland said.

“Starvation will be just around the corner unless we get there in the coming weeks,” he said.