Rio Tinto Group, the second-largest iron-ore producer, said the closure of a rail line at its Western Australian mines may extend into a fifth week.

Rio said Feb. 17 it halted some mining operations and rail movements as lines connecting its Pilbara mines with the coast were flooded. It told clients a week later it may defer February and March shipments by declaring a force majeure, a legal clause that allows delays if an incident happens outside a supplier’s control, according to a letter Bloomberg obtained at the time.

“We don’t expect to reopen the Pannawonica line, servicing Mesa J mine, for another week,” Perth-based spokesman Gervase Greene said yesterday in an e-mailed response to questions from Bloomberg News. Mesa J is part of the Robe River mine complex connected by the line to Cape Lambert port, the company’s Web site shows.

The disruption comes as iron ore producers negotiate annual benchmark contract prices with consumers of the steelmaking raw material for the year starting April 1. Goldman Sachs JBWere Pty yesterday cut its contract price forecast to a record 40 percent decline because of slumping global steel production. Contract prices rose for a sixth straight year to a record last year.

Rio’s London-based spokesman Nick Cobban said the company doesn’t comment on any force majeure. Cobban said last week partial resumption of rail services had begun on Feb. 28. While berthing and ship loading resumed, the force majeure was still in place, Inchcape Shipping Services Pty Ltd. said last week.

Pilbara is where most of Australia’s oil, gas and iron-ore production is located. Rio’s 11 mines in the area produced 175 million metric tons last year, the company said on Jan. 15.

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