Leading shipping companies including Greek operators have called for amendments to a United Nations proposal aimed at cutting marine fuel emissions, warning the draft deal may not support decarbonisation or fair competition, reports Reuters.

The group, which includes Frontline of Cyprus and Saudi Arabia's Bahri, expressed "grave concerns" over the Net-Zero Framework set for adoption next month by the International Maritime Organisation's environmental committee.

In a joint statement, the companies said the framework lacks realistic implementation paths and could impose excessive financial burdens and inflationary pressure on consumers. They urged critical revisions before the deal is finalised.

The United States has opposed the draft, warning countries they could face tariffs, visa restrictions and port levies if they support the accord.

IMO Secretary-General Arsenio Dominguez said he remains confident the deal will be adopted, citing the organisation's history of cooperation and commitment to addressing concerns.

Greek Shipping Minister Vassilis Kikilias echoed industry worries during London International Shipping Week, saying improvements are needed. The shipping ministry confirmed his support for the sector's position.

About 90 per cent of global trade moves by sea, and emissions are projected to rise without a binding mechanism. The April draft agreement includes fees for ships breaching carbon standards.

The statement was co-signed by Capital Group, TMS Group, Centrofin, Marine Trust, Trust Bulkers, Common Progress, Dynacom, Dynagas, Emarat Maritime, Gaslog, Hanwha Shipping, Angelicoussis Group, Seapeak and Stolt Tankers.