Kerry Stokes' Seven Group Holdings has finally accepted Mitsui's takeover offer for its shares in oil and gas play AWE and is now backing the Japanese giant to operate the prized Waitsia gas field in Western Australia despite earlier calling for that role to pass to partner Beach Energy.

Seven Group's acceptance of the $602 million offer propelled Mitsui above the 90 per cent threshold for its interest in AWE, which will allow it to move to 100 per cent ownership. Mitsui said late Wednesday it has now secured 93.19 per cent of AWE and extended its 95¢-a-share offer, which was due to close on Wednesday, until May 2.