.Men killed in city's Mezzeh neighbourhood were suspected of aiding rebels, opposition activists say
.Government forces launch helicopter gunship attacks in areas of capital which had once been held by rebels
.Syrian state TV denied the government was using helicopters and said the capital was calm
.News of the helicopter attacks emerged as Syrian rebels launched an offensive to 'liberate' the country's largest city of Aleppo
.Death toll has risen to more than 19,000 since the uprising began in March last year
At least 20 unarmed men were executed by Syrian troops after they were suspected of aiding rebels in the country's war-torn capital Damascus, it was claimed today.
The men, who were aged about 20 to 30, were killed in the city's Mezzeh neighbourhood, opposition activists said.
The killings were reported as regime forces appeared to have regained control of the capital after days of bloody street battles.
Activists said the bodies of 20 men were collected from the neighbourhoods of al-Ikhlas, al-Zayat, al Farouk, Hawakir al-Sabbarah and al-Basatin.
One of the activists, Bashir al-Kheir, said: 'The bodies were taken to al-Mustafa Mosque.
'Most had bullet holes, one with as many as 18. Three had their hands tied behind their back.
'Some of the men were in their pyjamas. Several had their legs broken or fingers missing.
'Others were stabbed with knives.'
Video footage and photos posted by activists on the internet purportedly showed the bodies on the mosque floor.
One bore what appeared to be torture marks on the stomach. Two men appeared to have had their throats slit.
The videos emerged after it was reported that the Syrian government had used helicopter gunships against rebel fighters in Damascus, causing heavy casualties.
The Syrian Observatory for Human Rights reported heavy attacks by government forces in the neighbourhoods of Mazzeh and Barzeh which had once been held by rebels.
Syrian state TV denied government forces were using helicopters and said the capital was calm and troops were just mopping up the remnants of the 'terrorists' in cooperation with residents.
Read more on Daily Mail