The gas show was recorded from points C1 to C4, and 12m of core has been cut with a second core being run.

The forward plan is to establish the thickness of the Toro reservoir and then continue drilling to the Imburu Sand structure underneath.

Rift will run wireline logs once the total depth of 1900-2000m is reached.

"We are delighted with the continuing success of the drilling at Puk Puk-1 and look forward to reporting further as the operation continues," Rift chairman Ian Gowrie-Smith said.

In previous drilling Rift reached the upper reservoir of the Alene Sand, some 150m higher than expected, and the company said it observed increased gas levels similar to those experienced in the drilled Douglas-1 well, some 25km from Puk Puk-1.

Rift said flow testing of Puk Puk-1 should be complete by the end of July, when the field's potential can be accurately assessed.

The planned flow testing at Douglas-1 will follow with the well expected to be assessed by the end of August.

Rift Oil recently signed a heads of agreement with Flex LNG to jointly develop and market Rift's onshore PNG gas reserves using a floating liquefaction unit.

Flex, a Norwegian floating LNG specialist, said the project is expected to produce about 1.5 million tonnes per annum of LNG with start-up targeted for the first half of 2012.

Rift and Rio Tinto Alcan also signed a non-binding memorandum of understanding late last year to investigate the supply of around 40 billion cubic feet per annum of natural gas to Alcan's Gove Alumina plant, in the Northern Territory, for 20 years after initial production is achieved.

The supply of the gas - should sufficient reserves be proven - was proposed to be via a direct pipeline covering 300km from the Douglas discovery to the coast then another 600km offshore to the Gove alumina complex.

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