The company said the designated authority approved Petrobras' acquisition of a 50% interest in WA-360-P and registered the Brazilian giant on the permit title.

Petrobras was named the farm-in partner for WA-360-P in April, with the farm-in representing the company's initial entry into Australia.

Under the agreement, Petrobras will earn a 50% interest in the permit by funding 100% of the first well, Artemis-1, to a cap of $US41 million ($A43.7 million).

Once all approvals for the farm-in have been received, Petrobras will pay MEO a cash bonus of $US31.5 million and reimburse the company's share of past costs of around $US7.5 million.

MEO said it would now invoice Petrobras for the cash bonus and seismic-related back costs.

The 12 trillion cubic feet Artemis prospect is expected to be drilled once the Songa Venus semi-submersible rig is released from Shell in early November.

Meanwhile MEO's purchase of a 5% stake in WA-360-P from permit partner Moby Oil and Gas has become unconditional.

Moby said the $US7 million sale agreement received all the necessary regulatory approvals and a deposit of $US1.5 million has been received.

The balance of the sale is payable within five business days of the date MEO receives the cash consideration to be paid by Petrobras.

Following the Petrobras farm-in and MEO purchase, participants in WA-360-P will include: Petrobras (50%), MEO (25%), Cue Energy Resources (15%) and Moby Oil and Gas (10%).