A Syrian army assault killed more than 100 civilians on the outskirts of Homs on Tuesday, according to the Syrian Observatory for Human Rights.
Women and children were among the 106 people reportedly killed in the attack on the Basatin al-Hasawiya district on the outskirts of Homs city, the opposition crisis monitor reported on Thursday.
The Observatory said the area had become a refuge for about 1,000 people who had fled fighting in central Homs districts.
It said many of the dead were killed by shooting or stabbing and by fire that raged through homes after the assault.
The United Nations estimates more than 60,000 people have been killed since the conflict in Syria began, although it warns the real figure might be much higher.
Earlier on Thursday, another monitoring group estimated that more than 1 million Syrians had been imprisoned during the conflict that broke out in March 2011, and almost all detainees had been tortured.

Syrian rebels launch a missile near the Abu Baker brigade in Albab, 30 kilometres from the northeastern Syrian city of Aleppo, on Wednesday.