The Shakrok prospect could potentially contain a hefty 650mln barrels of oil and, with a 20% stake in the exploration venture, a success would be very significant for Petroceltic.

Total and CNPC each now own a third stake in the Bokhtar venture, in Tajikistan, and the partners will pay for the bulk of next year's work programme.

Shares edge close to new high after 30% upgrade to inferred resource and identification of potential high grade zones.

The proposed partnership was first agreed in December and at the time Tethys described it as a ‘tremendous deal’ which validates the asset’s world class potential.

The investment banking heavyweight has upgraded its rating to ‘buy’ from ‘neutral’ and has significantly increased its target price to £11.50 from £8.86.