Japanese company Mitsui is preparing to declare its A$602 million (US$468.4 million) takeover offer for Australia's AWE unconditional next week if it acquires at least 50.1% of its target's shares by 14 March.

By Wednesday of this week Mitsui held only 3.01% of AWE shares and said its deadline would mark more than a month since the launch of its bid and argued that gave ample time for AWE shareholders to assess the merits of the deal or for a rival offer to emerge.