At least four major Chinese steel mills have started diverting orders of Australian coking coal to other countries as a ban on shipments takes effect, analysts said.

Chinese steel mills and state-owned utilities revealed over the weekend Beijing verbally ordered them to stop buying Australian coking coal, as well as thermal coal used in electric power generation.

The Australian government has refused to speculate the ban is a fresh salvo in a broader diplomatic tussle between the two countries, but some analysts have said it is likely politically motivated.

Officials in Canberra have suggested the move could simply be Beijing looking to manage domestic demand.