Exploration firm ircle Oil said preparations to drill an exploration well are now under way in its Tunisia permit after the company received written confirmation of a six-month extension.

The company said it expected drilling of the well in the South West Belli area of the Grombalia Permit would commence in the second half of the year.

The well will have an expected total depth of 1,350 metres.

"We are very pleased that preparations are now underway for the drilling of our exploration well in the Grombalia Permit. This type of fault-bounded structure has proven historically to be successful for drilling,“ chief executive Prof Chris Green said.

Circle has a 35 per cent working interest in the permit, with the remaining 65 per cent held by operator Exxoil Tunisie.