The UN Human Rights Council was deadlocked Friday over whether to send war crimes investigators to Yemen, a move being pushed by some EU states but fiercely resisted by Saudi Arabia.

A European Union resolution led by the Dutch and Canada, calls for a Commission of Inquiry (COI) to be dispatched to Yemen, where a Saudi-led coalition has been bombarding rebels since March of 2015.

The Saudis have, in a letter leaked to several media outlets, threatened economic and diplomatic retaliation against rights council members that vote for the Dutch/Canadian proposal.

Commissions of inquiry are the UN’s highest level probes and have turned up evidence of war crimes and crimes against humanity in crisis-hit countries like Syria, North Korea and Burundi.

The Arab group in the 47-member rights council has put forward a milder proposal, which calls for a team of three experts to be sent to Yemen to “carry out a comprehensive assessment into all alleged violations” and to then engage with Yemen’s domestic inquiry.

The UN rights chief Zeid Ra’ad Al Hussein has repeatedly called for the more robust COI and said that the Yemeni national inquiry is not capable of conducting a meaningful probe.

The two camps were due to agree on a compromise text on Friday morning but the deadline has repeatedly been pushed back.

Council spokesperson Rolando Gomez said discussions were ongoing. Countries with significant and lucrative ties to Saudi Arabia, including the United States, Britain and France, were reported to be seeking a compromise between the two camps.

The Saudi-led coalition has been accused of bombing schools, markets, hospitals and other civilian targets in Yemen, where they intervened to support President Abedrabbo Mansour Hadi.

Hadi says the Huthi rebels are supported by Saudi’s regional arch-rival Iran.