Trade sources said on Wednesday ship queues had risen for a second week due to unplanned maintenance at the port and as wet weather slowed production at some mines leaving some vessels short of cargo.
Exports from the eastern coast port, which ships mostly thermal coal used in power generation, rose to 1.85 million tonnes in the week to July 6, port data showed.
Ship queues stood at 49 as of Tuesday, according to data from the Web site of the Hunter Valley Coal Chain Logistics Team (HVCCLT), which coordinates coal movements from mines to the port.
Of the 49 vessels waiting to load coal, 13 had coal availability issues while an additional seven did not have coal available when they arrived, HVCCLT said.
The number of coal ship arrivals, a key indicator of demand, also rose by four to 24, while waiting time for vessels scheduled to load coal fell to 11.7 days.