Port authorities at Australia's Port of Newcastle — the country's largest thermal coal port — have suspended loading operations for the next 24 hours because of debris in the port waters, according to several market participants.

Severe rain caused flooding across Hunter River tributaries — a key region for coal mining operations. Significant debris has entered port waters because of "runoff from surrounding catchment areas", according to a notice issued by the port authority.

Operations have been restricted to daylight hours and only one outbound coal vessel is scheduled on 24 May. Authorities are monitoring the situation to determine any further restrictions for vessel movements.

Rail deliveries on the Hunter Valley rail network are also affected from floods. Publicly-owned operator the Australian Rail Track (ARTC) has closed all lines at the Sandgate and Kooragang North Fork after combined high tides and heavy overnight rain reaching 149mm in Newcastle, in an update issued on 23 May.

The ARTC said services will remain suspended until after assessments are completed on 24 May. Its staff are conducting inspections and will bring services forward if the flooding recedes. The rain band over the Hunter region is moving south and no rain is predicted across the New South Wales on 25 May, according to the ARTC. Flood levels at the Hunter River is steady between minor to moderate.

These disruptions come after another round of rail closures and port delays this week because of heavy rain and floods.

By Nadhir Mokhtar