OCEAN shipping lines are deploying sweeper and extra-loader vessels to Australia “at a high financial cost” to help clear the empty container build-up, Shipping Australia says.

In a statement published on its website, Shipping Australia said the willingness of shipping lines to make direct cost outlays and forego revenue to reduce the empty container backlog showed the “incredible support” being given by ocean carriers to keeping Australia’s supply chain functioning.

“If a ship has two thousand imports and is only allowed 2500 exchanges, then only 500 boxes can be exported,” Shipping Australia CEO Rod Nairn said.

“Container congestion is inevitable unless additional calls are made just to pick up exports. Our members are paying for extra ships and extra port calls in an effort to alleviate the problem. But this comes at a cost.”

Congestion around Port Botany has been a major issue in recent months.