The upper reservoir Alene Sand objective was reached at a depth of around 1760m with Rift saying the increased gas levels observed were similar to those experienced in Douglas-1.

"We have found gas, importantly 150m higher than expected which is a great sign," Rift chairman Ian Gowrie-Smith said.

"We are exceptionally pleased with the indication that Puk Puk-1 is a gas discovery, further confirming our belief that our assets in Papua New Guinea have the potential to become commercial projects."

Wireline logs are planned for when drilling reaches a target depth between 1900-2000m with the Toro Sand main reservoir objective now expected to be penetrated below 1820m.

Rift said flow testing of Puk Puk-1, which is being drilled by its Coral Sea rig, should be complete by the end of July at which point the potential of the field can be accurately assessed.

The planned flow testing at Douglas-1 will follow with its assessment completed by the end of August.

Puk Puk-1 in PPL 235 is targeting estimated recoverable reserves of about 226 billion cubic feet of gas and is targeting a separate structure from Rift's Douglas gas discovery.

PPL 235, which includes the Douglas gas field that was discovered in 2006, has estimated reserves of about 798Bcf.