Significant changes to the verification of container weights coming into effect this summer could spark chaos at UK ports, according to haulage companies.

Amendments to the Safety of Life at Sea (Solas) Convention will make shippers responsible for ensuring containers have a verified gross mass before they can be loaded on to a vessel for export.

Ports including Liverpool and Felixstowe have announced plans to offer a weighing service, but container hauliers have warned it could result in crippling queues. “The problem will be when we get into the port,” said Goldstar MD Matthew Ashworth. “It will delay us.”

Paul Miller, MD at Macintyre Transport (which was acquired by Turners (Soham) in January), said it already had issues with Felixstowe’s vehicle booking system and that additional queues for weighing purposes could mean time slots are lost.

“We are going to be driven by the shipping lines and what the ports are going to do. We could have another Operation Stack on our hands.

“It’s the export side that concerns me more, if the port isn’t geared up or it starts to cause a delay. How are they going to police weighing containers?” he said.

Chris Abbott, general manager at James Kemble, described the legislation as ill-considered and cast doubt on Felixstowe’s arrangements for weighing containers.

He added that further changes due to come into effect in 2017 put the onus on hauliers to get containers weighed. “That will be a nightmare,” he said.

Felixstowe port said the rules “have the potential to cause significant disruption” but a spokesman said there would be a couple of weighing stations for hauliers to use.

“We have decided to offer a container weighing service but there is uncertainty at the moment about how many will avail themselves of this service,” he added.

A spokeswoman at Liverpool port said: “We intend to weigh every container.”