Inpex managing executive officer Mashiro Murayama told a quarterly earnings call on Friday that Ichthys was 74% complete as of June, four or five percentage points behind target.

"It's delayed by about a quarter," Murayama said.

"To recover, we have been trying hard, adjusting various schedules and so on."

The Japanese major also announced on Friday that a number of marine vessels were now in Darwin Harbour working near the marine offloading facility, which is now operational, and the jetty near Bladin Point, the hub of the Ichthys project's onshore LNG facility construction site.

The giant Ichthys gas and condensate field in the Browse Basin was the largest discovery of hydrocarbon liquids in Australia in 40 years when Inpex Australia found it in 2000, about 220km offshore Western Australia.

Ichthys is a joint venture between operator Inpex, Total, CPC Corporation Taiwan and the Australian subsidiaries of Tokyo Gas, Osaka Gas, Kansai Electric Power, Chubu Electric Power and Toho Gas.