Ships laden with Australian coal are sitting in limbo off the coast of China, caught short by import restrictions.

Beijing imposed import restrictions earlier this year in the hope of boosting domestic coal prices, but has given no indication of when they might be lifted.

Minerals Council of Australia CEO Tania Constable says it has left companies “deeply concerned”.

“We believe an unofficial quota system [has been] employed since the restructure of customs and quarantine administrative arrangements in October 2018,” she said.

“It would have a significant impact on the industry if [restrictions] extend for too long.”

Vivek Dhar, a commodities analyst at Commonwealth Bank, says Beijing is looking inward, and away from Australian coal.

“[Chinese] policy on coal has very dramatically shifted over the last three to four years, but particularly over the last year [as] import restrictions have been fiddled with,” he told the ABC.

“Mid-November is where we saw the most aggressive push towards a policy of capping coal import levels and that was probably the most prominent move, similar to this, we've seen.”

Ms Constable said talks at the Chinese embassy in Canberra are underway.

“The longer these sorts of delays go on, of course it does have an effect overall on production and that has a flow-on effect to other parts of business,” she said.

“A lot of discussion is occurring with customers in China and with the traders themselves, and plans are being made to try and get to the bottom of it.”