The measured and indicated resource is now over 1.4 million ounces of gold, while the grade also rose 57% to 1.35g/t gold.

The interim resource update used the results from the 10,525m of diamond drilling over 63 holes since the last resource update at the end of January.

It also extended the resource boundary 1,040m, or 47%, along strike to a total length of 3,200m.

Chaarat technical director and head of exploration Dorian Nicol said the new geological model was "robust" and comprised two domains of higher and lower grade gold mineralisation within a structurally bound corridor. 

"This geology-driven model demonstrates increased continuity of higher grades compared to the previous statistically driven model," he said.

Chaarat said it was aiming to complete around 30,000m of diamond drilling at the Tulkubash this year, with another resource update expected in the March 2019 quarter and an updated reserve due next month.

The company said the drilling had helped it gain a "better understanding of the distribution of oxide mineralisation within the Tulkubash deposit", which it would combine with the results of the recent metallurgical test programme to forecast recoveries more accurately. 

It added that it now also had a "better understanding of the local variability and controls on mineralisation within the mineable resource, which will provide an excellent basis for short-term mine planning".