NATHAN Tinkler has doubled the projected size of the coal-loader he wants to build on the former BHP steelworks site.

The Tinkler camp has confirmed plans for an ‘‘enhanced’’ version of the loader revealed in December by the Newcastle Herald.

The new proposal would be built in stages over a decade, cost ‘‘well over $1billion’’ and handle up to 100million tonnes of coal a year.

Mr Steve van Barneveld, managing director of the Tinklercompany Hunter Ports, said yesterday the former steelworks site had the potential to be the best site for extra coal terminal capacity in Newcastle.

The proposal is sending shockwaves through the Hunter coal industry, which had agreed with the previous state government to concentrate its expansion plans across the river on Kooragang Island.

The Tinkler proposal is also opposed by the two government agencies controlling the steelworks site, the Hunter Development Corporation and Newcastle Port Corporation.

The Tinkler group gained a foothold on the steelworks site when it bought into Newcastle property company Buildev in late 2008.

At the time, Buildev was one of three companies shortlisted by the development corporation to develop its inland 62hectares of the steelworks site as a port-related industrial park.

Buildev won the tender in December 2008.

The decision to ditch the business park in favour of the coal-loader is believed to be linked to another Tinkler asset, the planned Maules Creek open-cut mine near Narrabri, and plans for a Tinkler fleet of coal rail trains with their own service centre at Singleton.

Development corporation general manager Bob Hawes said yesterday the corporation was opposing the plan after advice from lawyers and probity experts that Buildev’s competitors did not get the chance to bid for a coal terminal.

A port corporation spokesman said its plan for a multi-cargo shipping terminal on its 90hectares of steelworks land was ‘‘vital’’ to the future of the port.

‘‘A coal terminal on the port side land component of the Mayfield site is inconsistent with the Mayfield concept plan,’’ he said.