More than 60 non-governmental groups urged the United Nations to ensure war crimes and human rights abuses in Yemen's conflict are documented and investigated to ensure accountability.
Activist groups have called on the UN General Assembly to create a new panel of independent experts to collect and preserve evidence of possible war crimes by all sides in Yemen's bitter conflict for future prosecution.
Some 60 groups, including Human Rights Watch and Amnesty International, called in a joint statement on Thursday for a fresh investigation.
They accused Saudia Arabia and the United Arab Emirates of an "aggressive lobbying campaign" to quash that Geneva-based expert panel set up four years ago.
Bahrain, Russia and other members of the UN Human Rights Council pushed through a vote in October to shut down its war crimes investigations in Yemen, in a stinging defeat for Western states.
"For too long, parties to the conflict in Yemen, including Saudi Arabia and Houthi forces, have committed atrocities with impunity," Agnes Callamard, secretary-general of Amnesty International, told a press conference.
The United Nations had failed the Yemeni people who have endured years of widely-documented suffering, she said.
"Bullying and bribing and corruption of the system has won the day," Callamard said.
"Saudi Arabia and the UAE and their allies shamelessly and aggressively lobbied states through their capital cities and got rid of the Group of Eminent Experts."
"There is a deadly vacuum of accountability in Yemen. That's because the Saudi government killed the one existing mechanism," said Ken Roth, executive director of Human Rights Watch.
Saudi officials had "bribed, coerced and arm-twisted" member states of the Human Rights Council, defeating the resolution, Roth said.
The groups did not offer proof of the bribery and bullying allegations.
But Roth, echoing comments by Western diplomats in Geneva, said Saudi officials had warned Indonesia and possibly other Muslim majority countries that they should vote against the probe if they wanted their nationals to have access to the Haj pilgrimage in Mecca.
More than 100,000 people have been killed and 4 million been displaced in the war marked by Saudi-led coalition air strikes as well as shelling and missiles by Iran-aligned Houthi fighters.
The Saudi-led Sunni Muslim coalition intervened in Yemen in March 2015 after the Houthis ousted the internationally recognized government from power in the capital, Sanaa, in 2014.