In its ruling, the panel said the Whitehaven merger proposal denied Gloucester shareholders the ability to consider significant changes.

The panel also said the merger proposal would have an effect on the control or potential control of Gloucester.

In another finding, the panel said the merger proposal prevented an auction for control of Gloucester and denied the company’s shareholders an opportunity to participate in Noble’s bid for the company.

Noble, a 21.7% shareholder of Gloucester, launched an off-market cash takeover of the coal producer at $4.85 per share, which was 54.2% higher than Gloucester shares before the initial merger announcement.

The cash takeover offer followed Noble’s application to the Takeovers Panel, with the strategy successfully putting the brakes on a possible merger between Gloucester and Whitehaven.

Noble has previously said Whitehaven’s shareholders would have ended up controlling 67% of the merged entity with four current Whitehaven directors controlling more than 50% of the merged entity.

The merger structure also did not allow Gloucester shareholders a vote on whether the merger should go ahead, as confirmed by the Takeovers Panel’s decision.

Back in 2007, Hong Kong-based Noble and private mining group AMCI used their stakes to vote down a takeover offer by Xstrata Coal, despite the wishes of Gloucester’s board.

Shares in Gloucester last traded up 13c to $4.73, while Whitehaven shares are down 4c to $1.54.