Takeover target AWE has lifted its estimate of gas reserves in its Waitsia field north of Perth by a significant 80 per cent, but one of its two bidders is giving no sign it is yielding to pressure to up its offer.

Reserves at the field are now put at 820 petajoules, thanks to positive results from drilling and testing at recent wells, said AWE, which holds 50 per cent of the resource. The company had flagged the upgrade last month after reporting the results of an independent review by consultancy RISC.