The United States has warned it may impose visa restrictions, port bans and sanctions on countries backing the UN's International Maritime Organization's IMO Net-Zero Framework to tax shipping emissions, reported Reuters.

UN member states are vote on IMO proposal, which aims to tax carbon dioxide emissions from shipping, which is responsible for more that two per cent of greenhouse gases.

US Secretary of State Marco Rubio, Energy Secretary Chris Wright and Transportation Secretary Sean Duffy said the administration "unequivocally rejects��the proposal, calling it a threat to the global economy and a "punitive and regressive��tax regime.

The US is considering retaliatory measures against supporting nations, including blocking flagged vessels from US ports, imposing visa fees and targeting officials behind climate-focused policies.

While major container carriers support a global framework to accelerate decarbonization, some of the world's largest oil tanker firms have voiced "grave concerns��over the plan.

Supporters argue that without a unified global standard, the maritime industry risks facing a fragmented system of regional rules that would raise costs without effectively cutting emissions.