Amnesty International accused both the Saudi-led coalition carrying out air strikes in Yemen and the forces on the ground, supporting or opposing the Houthi rebels.
The London-based rights group said the violence has been particularly deadly in the southern city of Aden and in Taiz, with dozens of children among those killed.
Yemen's conflict pits the Houthis and troops loyal to former president Ali Abdullah Saleh against forces including southern separatists, tribal fighters and troops loyal to President Abd-Rabbu Mansour Hadi, who is in exile in Saudi Arabia. The Saudis are leading a US-backed Arab coalition that is carrying out air strikes against Houthi fighters.
"Civilians in southern Yemen have found themselves trapped in a deadly crossfire between Houthi loyalists and anti-Houthi groups on the ground, while facing the persistent threat of coalition air strikes from the sky. All the parties to this conflict have displayed a ruthless and wanton disregard for the safety of civilians," said Donatella Rovera, Amnesty's senior crisis response adviser.
"The report depicts in harrowing detail the gruesome and bloody trail of death and destruction in Taiz and Aden from unlawful attacks, which may amount to war crimes, by all parties," Amnesty said.
Fresh strikes
Meanwhile, jets from the Saudi-led coalition targeted rebel Houthi positions in Yemen's Red Sea port of Hodeida early on Tuesday, port officials said, destroying cranes and warehouses at a main import hub for critical aid supplies to the country's north.
There were also clashes further south overnight in Yemen's third city, Taiz, Arab television stations reported, as local groups opposed to the Houthis attempted to consolidate recent advances to take the city.
