Saudi-led coalition and Houthi rebels fighting in Yemen targeted civilians in "widespread and systematic" attacks and some of the operations could be seen as a crimes against humanity, United Nations sanctions monitors stated in its report to the UN Security Council.
The UN experts from the sanctions monitors documented 119 Saudi coalition strikes "relating to violations of international humanitarian law" and said that "many attacks involved multiple air strikes on multiple civilian objects."
The experts also underlined all warring parties in the conflict were breaking international humanitarian law.
The experts also accused the Houthi rebels and their allies - forces loyal to former Yemen President Ali Abdullah Saleh - of carrying out systemic attacks against civilians, homes and hospitals and these could be crimes against humanity as well.
The experts called on the 15-member UN Security Council to consider setting up a Commission of Inquiry to investigate such cases over violations of international law.
The Saudi UN mission did not make a comment.
The report triggered human rights groups to call on the United States and the UK to suspend arms sale to Saudi Arabia stating that weapons may be used in such attacks.
"The US and UK governments should immediately halt the transfer of any arms to the Saudi-led coalition that might be used for such violations, and they should back an international investigation into abuses committed by all sides," stated Philippe Bolopion of international rights group Human Rights Watch.
The UK Prime Minister David Cameron told parliament on Wednesday that he would read the UN report but that Britain followed "the strictest rules for arms exports of almost any country anywhere in the world."
The US State Department spokesman Mark Toner announced the United States was concerned about the claims regarding violations against international law in Yemen.
He called on both sides to follow international humanitarian law, "including the obligation that they distinguish between military objectives and civilian objects, and to take all feasible actions to minimise harm to civilians."
The US and Saudi officials are working to complete a $1.29 billion deal for the sale of smart bombs and other weaponry to Saudi Arabia to replenish its depleting supplies after operations in Yemen and Syria. It should be finalised in coming months.
Over 19,000 smart bombs have to be urgently delivered in order to make up for the depleting supplies.
As part of violation of a UN arms embargo, the UN experts are also examining anti-tank guided missiles originating from Iran to the Houthi and Saleh forces after the weapons were seized off the coast of Oman in September by US and Australian warships.
Iranian-backed Houthis have been battling the Saudi-led coalition since late March.
As a result of Houthi aggression, Yemeni President Abd Rabbuh Mansour Hadi had to temporarily flee to the Saudi capital Riyadh and formally request help from Arab states to save Yemen from the Houthi militants.
Meanwhile, Gulf Arab countries and the US have accused Iran of assisting the Houthi militants financially and militarily.
According to the United Nations, at least 6,000 people have been killed in the ongoing civil war in Yemen, nearly half of them civilians and more than 27,000 have been injured since March.