The Syrian regime is causing high civilian casualties in opposition-controlled areas of the northern city of Aleppo, Human Rights Watch said Saturday, dpa reported.
Its air and missile strikes so far have killed 84 people in Syria's main commercial hub, the New York-based rights watchdog said.
"In attack after attack in Aleppo, it is only civilians and civilian homes that are hit by government airstrikes," said Anna Neistat, the group's associate programme and emergencies director.
"The information collected by Human Rights Watch shows that the Syrian government continues to use banned cluster bombs and indiscriminate methods of attack in populated areas, making the airstrikes unlawful," Human Rights Watch said.
Its researchers documented five attacks that took place from March 18 to April 7 during a recent week-long mission to Aleppo, Neistat said.
Government troops and rebels have battled for months over the control of Aleppo with each side claiming major gains.
The Syrian government has repeatedly denied using ballistic missiles or cluster bombs during the two-year conflict, which has killed about 70,000 people, according to UN estimates.