A consortium of coal mining firms has offered to buy Queensland's coal track network for $4.85 billion.

Queensland Coal Industry Rail Group (QCIRG) chairman Nick Greiner said the bid was made to counter a plan by the Queensland government to float Queensland Rail's coal and bulk freight assets by the end of the year in a new public company known as QR National.

According to Greiner, the offer represented a substantial premium to the value, which is likely to be achieved by the government's planned initial public offering (IPO).

"Importantly, our offer is able to be settled with the government prior to the IPO and will not be dependent on volatile equity markets, removing major risk for the state while also providing early settlement," Greiner said in a statement.

The offer is for the four systems of Central Queensland track network, and the Goonyella to Abbot Point expansion.

Greiner said QCIRG has secured a facility of $1.35 billion, underwritten by ANZ, NBP Paribas and Citibank NA and a committed capex facility of more than $2.05 billion to fund the existing QR capital plan and maintenance.

QCIRG is comprise of 13 coal producers, with Anglo American Metallurgical Coal, BHP Billiton, Ensham Resources, Felix Resources, Jellinbah Resources, Macarthur Coal, Peabody Energy, Rio Tinto Coal, Vale Australia, Wesfarmers Resources and Xstrata Coal. All companies have signed equity subscription agreements. Aquila Resources and New Hope Coal Australia are supporting parties and may provide equity at a later stage.