BHP Billiton is voicing concern over a potential strike at Port Headland, Australia’s No. 1 export port, by the Maritime Union of Australia (MUA) and other labor unions.

Shipment interruptions, said BHP, would negatively impact Australia’s worldwide reputation as a stable and reliable minerals supplier, said BHP Iron Ore President Jimmy Wilson; the port lies in Western Australia’s Pilbara, it’s most iron-ore prolific region.

Such a walkout, according to company representatives, will cease all port shipments, costing exporters like BHP Billiton, Fortescue Metals Group, and Atlas Iron $92 million per day amid already tough economic conditions; the state and federal government, meanwhile, could lose tens of millions daily in royalties and corporate tax revenue.

BHP Billiton said it is worried about talks between Teekay Marine Pty. Ltd and the maritime unions over so-called enterprise bargaining agreements. Union reps, said BHP, seek an excessive annual salary increase close to 10%, with annual leave noncommensurate with productivity.

Port Headland maritime union employees, however, are already among the highest-paid in Australia’s towage industry, BHP added in a statement, making the demands “unreasonable and out of touch with the current economic conditions faced by Australian exporters.”