The rules governing global shipping are breaking down, the world's largest maritime nations have warned, disrupted by wars and a growing shadow fleet that operates beyond western oversight. The shipping industry has for decades been protected by laws that ensure free navigation and the neutrality of commercial vessels, but the collapse of those principles is posing a severe risk to global trade, according to a group of 18 shipping superpowers. Without maritime trade, supply chains would fragment and the global economy as we know it would come to a sudden halt, the group said in a statement.

The battle to control the Strait of Hormuz, the Covid-19 pandemic, and the shadow fleet created as a result of US, EU and UK sanctions are not episodic shocks but signals of a structural shift in the operating environment of global trade, said the Consultative Shipping Group, whose members represent more than a fifth of global trade by tonnage. The group's members include Greece, Singapore, Denmark, Japan, Canada, the UK, the Netherlands and South Korea. Shipping routes are increasingly instruments of leverage and risk, the CSG warned, adding that recent events show how fragile the system of maritime trade can be.

For decades, we have built global trade on the assumption that ships can move freely across borders. That assumption is now under pressure, said Brian Wessel, director-general of the Danish Maritime Authority, which chairs the CSG. The global level playing field and the global regulations that we've made for many, many years in the IMO have been taken for granted.

More than 80 per cent of world trade is transported by ships, which operate under rules set by the IMO. The body itself was formally created in 1948 but the concept of international governance of the oceans stretches back to the 17th century when the idea of mare liberum, or free seas, was first established. Because of their role in global trade, vessels have become an increasingly prominent target and pawn in geopolitical machinations.

Russia, Ukraine, the US and Iran have all hit civilian shipping targets during conflicts this year, while the vulnerability of maritime chokepoints has been underscored by Iran's efforts to try to establish a fee-paying regime in the strait. Tehran said a deal with Oman to manage shipping through the waterway, through which about a fifth of the world's oil and gas previously flowed, was close to being agreed. It is not clear whether a toll will be charged.

At the same time, US, EU and UK sanctions on Russia and Iran have caused the rapid growth of a shadow fleet of oil tankers that now amounts to more than 1,500 vessels, according to Tanker Trackers.com, almost a fifth of the global tanker fleet. Nearly all these lack traditional insurance policies. This summer, the Caroline Bezengi, a shadow fleet ship carrying roughly 800,000 barrels of Russian oil, hit a limpet mine off the coast of Oman without any traditional protection and indemnity insurance, potentially leaving the Omani government on the hook for millions of dollars of costs related to the clean-up.