The wet weather has continued in December and at this stage it is expected that, while saleable coal production for the first half will be about 10% up on last year, it will fall short of budget by approximately 24% or 700,000 tonnes, the company said in a statement.

The news sent Whitehaven's share price down by 4% to $6.72 this morning, leaving it vulnerable to opportunistic takeovers.

Earlier this year, the company revealed it had set up a data room to deal with the overwhelming interest of suitors, some of which were major global companies keen to establish themselves in the Gunnedah Basin.

Whitehaven currently operates four open cut mines in the Gunnedah region: Rocglen, Sunnyside, Tarrawonga and Werris Creek.

In the five months ending November 30, 2010, Whitehaven lost a total of around 3200 operating hours across the four mines due to wet weather, compared to about 950 hours during the same period last year.

As a result of this, Whitehaven has increased its purchases of coal to meet fixed sales commitments, with a total of more than 1 million tonnes expected to be purchased for the first half.

"The need to purchase additional coal, particularly at a time when coal availability is generally low as a result of the wet weather and prices are rising, will have a significant negative impact on first-half earnings," the company said.

"Whitehaven is not yet able to estimate half-year earnings accurately, due to uncertainty around shipping at the end of December, but will be able to provide profit guidance to shareholders in January, ahead of the half-year reporting date."

In August this year Whitehaven announced it had been in discussions with third parties in relation to potential corporate transactions, and that those discussions which were continuing were preliminary and incomplete.

This followed speculation that a number of global parties were in talks for a takeover, including US-based Alpha Natural Resources.

A “formal process” will determine whether a proposal is available for the company at a price and on terms that are in the best interests of all shareholders and which will cause less disruption to the conduct of Whitehaven’s day-to-day business.