Syrian rebels claimed they downed a fighter jet yesterday in what would be a major coup for the opposition but the regime seized the upper hand in Aleppo as it advanced into a new rebel-held district.

Government forces also bombarded areas around Damascus and launched a wide sweep of the capital, including its once-bustling historic Old City.

State media said a military plane on a training mission crashed in the east of the country after suffering a malfunction and that the pilot had ejected.

But the Free Syria Army, which has been calling for the international community to arm it with anti-aircraft weapons as it battles escalating regime attacks from the sky, claimed it shot down the Russian-made MiG in the eastern province of Deir Ezzor.

“With God’s help, a MiG 23 plane was downed in Muhasen on Monday morning, by the hands of the Ahfad Mohammed (Grandchildren of Mohammed) Brigade,” said Captain Abul Laith, whose group is part of the FSA.

Another group calling itself the “Revolutionary Youth of the Land of the Euphrates” distributed a video showing a man identified as pilot Mufid Mohammed Suleiman, surrounded by three armed men.

“My mission was to bomb the town of Muhasen,” said the purported pilot.

If confirmed, the attack would be the first time the rebels have succeeded in downing a Syrian plane since President Bashar al-Assad’s regime launched an increasingly brutal crackdown on protests 17 months ago.

International concern is mounting over how to end a conflict that has triggered a major humanitarian crisis and sent around 140,000 Syrians fleeing to neighbouring countries, with scores of people being killed every day.

At least 87 lost their lives yesterday, according to the Syrian Observatory for Human Rights.

The opposition has accused the regime of increasingly resorting to firing from fighter planes, particularly on the second city of Aleppo which has witnessed some of the fiercest fighting in recent weeks.

An amateur video posted on YouTube by activists shows a fighter jet apparently being hit in a ball of fire, leaving a trail of smoke.

The incident occurred after umbrella opposition group the Syrian National Council issued a new appeal for the establishment of no-fly zones similar to those set up over Libya during last year’s conflict.

SNC head Abdel Basset Sayda said the rebels wanted “two no-fly zones, one in the north near the Turkish border, and another in the south near the border with Jordan,” in addition to “safe places for refugees and humanitarian corridors.”

Meanwhile, grisly footage of apparent atrocities in the Aleppo area emerged, appearing to show rebels callously throwing bodies off a post office building, while another video showed a man, blindfolded and bound, as his throat was savagely cut.

A crowd gathered around several bodies crumpled on the ground outside a building said to be in Al-Bab, near Aleppo, before another three victims were hurled one-by-one from the rooftop.

Syria’s army gained some ground as it advanced into a new rebel-held area of Aleppo, the northern metropolis seen as pivotal to the outcome of the conflict. “With tanks, Syria’s regime forces have stormed the west of the district of Saif al-Dawla,” said the Observatory. “They are now clashing with the rebels, and parts of Salaheddin are being shelled.”

Rebels in July took over several districts but regime forces last week reclaimed most of the Salaheddin district that neighbours Saif al-Dawla.

More than 21,000 people have been killed since March last year, with fighting escalating after the failure of outgoing international envoy Kofi Annan’s peace plan and the regime hit by an increasing number of defections by high-ranking officials.

The latest to flee yesterday was Syria’s top representative at the UN Human Rights Council.

Also yesterday, security forces arrested 22 residents in a major security sweep in the heart of Damascus, including the Old City, while shells slammed into rebel strongholds around the capital, according to the Observatory.

It was biggest operation of its kind in Damascus since the launch of the uprising, the Observatory said.