Australia's key coal port of Gladstone said devastating floods have left it so short of coal that a queue of ships waiting to load would likely be diverted elsewhere.

A deluge in Queensland state has flooded mines and damaged roads and railways, cutting the major Blackwater rail line that goes from the coal centre of Emerald through the flooded town of Rockhampton and south to Gladstone.

Queensland is a major world supplier of coking coal for use in steel-making, and the floods have pushed global prices up.

Although Gladstone itself was not flooded, a Gladstone Ports Corporation spokeswoman told Reuters only two trainloads of coal arrived last week, only two ships loaded and the coal arriving was only for domestic use.

"We have got about 18 ships sitting out waiting," spokeswoman Lee McIvor told Reuters. "We are expecting the coal companies to reallocate and reschedule these ships elsewhere."

On a normal day, Gladstone would receive around 24 trainloads of coal, McIvor said.

"We are getting shipments in but it's for domestic customers, not for export," she said, although she said there were hopes some export coal would arrive in the coming days.

The situation would persist for at least "a couple of weeks", she said. However, downpours over the weekend have brought new floods to parts of the state with forecasts of more to follow, brought by the La Nina weather phenomenon.

A spokesman for QR National, the state's main provider of coal transport by rail, told Reuters the company hoped waters would recede enough by the end of this week for an assessment of the Blackwater line to be made.

The northern line to Queensland's other major coal port, Dalrymple Bay, currently had surplus capacity, he said, and any shortages there were down to a lack of coal from the mines.

"It is a matter of getting coal provided by the mining companies," the spokesman said.

Dalrymple Bay's stockpile of coal has been running low at around 650,000 tonnes, but a spokesman said enough coal has been coming in to keep loading ships. Around 180,000 to 200,000 tonnes was coming in daily, said Greg Smith, a spokesman for port owner DBCT Management.

During the weekend, 22 trains were scheduled to come in, he said "It is hand to mouth, there's no two ways about that. Provided we can continue that type of in-loading rate then we will be able to continue processing the ships, probably about two per day," he said. (Reuters)