Rights watchdog Amnesty International called Tuesday for a UN-commissioned investigation into alleged war crimes committed during the Yemeni conflict that has killed more than 4,300 people since March.
In a report, Amnesty criticises "unlawful coalition airstrikes in densely populated residential neighbourhoods" as well as attacks in civilian areas by rebels and pro-government forces.
Fighting has intensified since March across the country after Iran-backed Huthi rebels and their allies entered President Abedrabbo Mansour Hadi's last refuge, Aden in the south.
Hadi later fled the country and on March 26, Saudi Arabia led a coalition of Arab states in carrying out a campaign of air strikes against rebel positions across Yemen.
"All the parties to this conflict have displayed a ruthless and wanton disregard for the safety of civilians," said Donatella Rovera, senior crisis response adviser at Amnesty.
"Civilians in southern Yemen have found themselves trapped in a deadly crossfire between Huthi loyalists and anti-Huthi groups on the ground, while facing the persistent threat of coalition airstrikes," said Rovera.
The report speaks of a "gruesome and bloody trail of death and destruction in (third city) Taez and Aden from unlawful attacks, which may amount to war crimes, by all parties."
It comes just one day after military sources reported more than 80 people killed in 24 hours of fighting between rebels and loyalists for control of Taez, a crucial gateway to the rebel-held capital Sanaa.
Loyalist forces have had coalition air support and advanced weaponry and troops reportedly supplied by Gulf countries, notably Saudi Arabia and the United Arab Emirates.
Rovera accused coalition forces of having "blatantly failed to take necessary precautions to minimise civilian casualties".
Amnesty called on the UN Human Rights Council to form an international commission of enquiry to investigate "alleged war crimes" committed during the conflict.
"Perpetrators of the callous attacks against civilians in Yemen need to know that they will pay the price and will be held responsible for war crimes," Rovera said.
"If the international community fails to investigate and hold violators to account then such attacks and the rampant killing and injuring of civilians is only likely to continue."
She also highlighted the "acute" humanitarian crisis in southern Yemen with essential services cut off, high food prices, damaged infrastructure and limited health care.
Last Tuesday, the World Health Organization said the conflict had claimed 4,345 lives from the escalation of fighting in March to August 5.
According to UN figures, half of those killed are civilians, and 80 percent of the country's 21 million people need aid and protection.