Iran has imposed an effective blockade on the critical waterway since the United States and Israel launched the war on February 28, sending ripple effects throughout the global economy.

Bahrain, backed by other oil-exporting Gulf countries, had launched negotiations two weeks ago on a draft resolution that would have given a clear UN mandate to any state wishing to use force to unblock the strait.

However, objections from several veto-holding permanent members have seen the text gradually watered down, and the vote -- originally scheduled for late last week -- has been delayed multiple times.

The latest draft, seen by AFP on Monday, still demands Iran end its attacks on commercial vessels and to halt "any attempt to impede transit passage or freedom of navigation in the Strait of Hormuz."

Instead of expressly authorizing force, it "strongly encourages States...to coordinate efforts, defensive in nature, commensurate to the circumstances, to contribute to ensuring the safety and security of navigation, including through the escort of merchant and commercial vessels."

It also encourages coordination "to deter attempts to close, obstruct or otherwise interfere with international navigation through the Strait of Hormuz."

The draft expresses the Council's "readiness to consider further measures" against anyone undermining freedom of navigation in the Strait.

The vote is scheduled for Tuesday at 11:00 am (1500 GMT), nine hours before President Donald Trump's deadline for Iran to agree to a deal or face attacks against its power plants and bridges.