BEIRUT — Activist groups said Sunday that about 5,000 people were killed in Syria’s civil war in August, the highest figure reported in more than 17 months of fighting as President Bashar Assad’s regime unleashed crushing air power against the revolt for the first time.
The UN children’s fund UNICEF put the death toll for last week alone at 1,600, the largest weekly figure for the entire uprising.
‘‘The past month witnessed large massacres, and the regime was conducting wide operations to try to crush the uprising,’’ said Omar Idilbi, a Cairo-based activist with the Local Coordination Committees group. ‘‘Last month’s acts of violence were unprecedented.’’
He said the increased use of the air force and artillery bombardments was behind the increase in casualties.
The civil war witnessed a major turning point in August when Assad’s forces began using air power for the first time to try to put down the revolt. The fighting also reached Syria’s largest city, Aleppo, which had been relatively quiet for most of the uprising.
The Britain-based activist group Syrian Observatory for Human Rights said that 5,440 people, including 4,114 civilians, were killed in August.
On Sunday, the Observatory and the LCC said more than 100 people were killed across Syria and the groups have been reporting 100-250 deaths per day during the past week.
Syria’s uprising has been the bloodiest in the Arab Spring that has already removed long-serving authoritarian leaders in Egypt, Tunisia, Yemen, and Libya.
The two main activists groups also released new death tolls for the entire uprising since March 2011. The Observatory said more than 26,000 have been killed, including more than 18,500 civilians. The LCC put the death toll at more than 23,000 civilians. The LCC does not count members of the military who are killed, but the Observatory does.
That averages out to about 1,300 to 1,500 deaths per month, making the August figure more than three times higher than average.
On Thursday, Human Rights Watch said government forces have killed scores of civilians during the past three weeks by bombarding at least 10 areas where they were lining up to buy bread at bakeries near and around Aleppo.
Last week, activists reported that between 300 and 600 people were killed in the Damascus suburb of Daraya during days of shelling and a killing spree by troops who stormed the town after heavy fighting.
In the latest violence Sunday, the Observatory said the military pounded rebel holdouts in Aleppo, the country’s commercial capital. There was also fighting in other areas including the central city of Homs, Idlib province on the border of Turkey and suburbs near Damascus.
The Observatory said 21 people were killed when troops stormed the village of Alfan in the central province of Hama. It added that eight people were killed in the oil-rich eastern province of Deir el-Zour that borders Iraq.
In the capital Damascus, two bombs exploded near the Syrian military’s joint chiefs of staff offices, lightly wounding four army officers and damaging buildings and cars, state television reported. The twin blasts in the posh Abu Rummaneh district were the latest in a wave of bombings to hit Damascus in recent months as fighting has escalated.