In a statement released one year into the Saudi-led intervention and titled "Reckless arms flows decimate civilian lives," the rights watchdog urged the two Western powers and other states to "halt all transfers of arms for use in the Yemen conflict".
"Saudi Arabia’s international partners have added fuel to the fire, flooding the region with arms despite the mounting evidence that such weaponry has facilitated appalling crimes and the clear risk that new supplies could be used for serious violations," said James Lynch, Amnesty International's regional deputy director.
Amnesty said that Washington and London, the largest arms suppliers to Saudi Arabia, "have continued to allow transfers of the type of arms that have been used to commit and facilitate serious abuses, generating a humanitarian crisis on an unprecedented scale."
The group said it has documented since the beginning of the conflict at least 32 air strikes by the Saudi-led coalition "that appear to have violated international humanitarian law".
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The strikes had killed "almost 361 civilians, including at least 127 children", it said.
Amnesty also accused the coalition of having "repeatedly used cluster munitions, inherently indiscriminate weapons whose use is prohibited, in attacks that have killed and maimed civilians."
UN Security Council Resolution 2216, adopted in April last year, imposed an arms embargo only on the Huthi rebels and their allies, forces loyal to former president Ali Abdullah Saleh, it said.
On February 25, the European Parliament called for an EU-wide arms embargo against Saudi Arabia, Amnesty said.
"In the absence of a Security Council embargo, Amnesty International is calling on all states to ensure that no party to the conflict in Yemen is supplied –- either directly or indirectly –- with weapons, munitions, military equipment or technology that would be used in the conflict."
The World Health Organization says fighting in Yemen has killed almost 6,300 people, half of them civilians, since March 2015 and the United Nations has warned of an unfolding humanitarian catastrophe.