Less than two weeks ago Bredero was declared the winner of the contract to coat the 889 km Inpex gas pipeline from the Timor Sea to Darwin.

But Bredero will do this work at its factories in Kabil, Indonesia and Kuantan, Malaysia.

Workers at Bredero's Kembla Grange plant have been told the company will shut its only Australian business in three weeks.

Meantime, the steel supply contracts have gone to Japanese companies, with Inpex saying Australian manufacturers lacked the capacity required.

Australian Workers Union assistant branch secretary Wayne Phillips said Bredero's Illawarra boss got a phone call from the company's headquarters in Canada last week telling them to close down the Kembla Grange facility "as soon as possible".

"It's a real shame," he said. "It's been a good steady employer for many people for many years."

Mr Phillips said up to 30 workers would lose their jobs, but when the plant had a big job - such as late last year - it would have employed more than 80 people.

"It's simply another area where some foreign boardroom has made decisions that affect Australian jobs," he said. "Everyone should be asking why. It's just wrong."

The Mercury sought comment from Bredero Shaw at Kembla Grange and Toronto but none was received.

The Top End pipeline is part of a $30 billion venture led by Japan's Inpex Corporation and French energy giant Total. Gas will be extracted from the Ichthys field and piped to Darwin where it will be processed for export, mostly to Japan.

Australian steelmakers have so far missed out on manufacturing work, with the steel to be imported from Japan and Europe. The pipe manufacturing contract for the project has gone to the Japanese companies Nippon Steel and Metal One, Inpex said last week. Bredero Shaw will do the pipe coating work in partnership with Mitsui Co.

Other companies involved in building the pipeline are Europipe, Sumitomo and Saipem.

Inpex public affairs manager Tim Larcombe said the steel suppliers were chosen from an open tender process, but no Australian business could make the pipe.

"The pipeline has a 42-inch diameter and, at 889 km in length, will be the longest subsea pipeline in the southern hemisphere," he said. "Our tender process confirmed that Australia does not have the capacity."