BHP said it expects it will take a week to clear the track and resume rail operations at its Pilbara iron ore operations after a massive train derailment that has raised serious safety concerns.

The mining giant was forced to deliberately derail a full-laden 2,6km-long iron ore train yesterday morning after the driver alighted to inspect a carriage and the train carried on unattended.

The train — with four locomotives and 268 wagons — careered for 92km at average speeds of 110km per hour before it was derailed near Turner, about 120km south of Port Hedland.

BHP said it derailed the train from its remote operations centre about 50 minutes later by switching a set of points on the track.

No-one was injured but the company this morning estimated that about 1.5km of track had been damaged in the incident.

“At this stage we anticipate the recovery process to take about one week,” a spokeswoman said.

BHP has not yet revealed what affect the incident will have on its full-year production guidance of between 273 million tonnes and 283 million tonnes.

The Australian Transport Safety Bureau sent two investigators to the site yesterday as part of an probe of the incident.

It is expected to provide a report on how the incident happened in the second quarter of next year. The report may make recommendations as to how rail operators can improve safety.

The Office of the National Rail Safety Regulator has also sent two investigators to the accident scene to investigate whether there had been any breach of the Rail Safety National Law.

BHP will conduct its own investigation.

“We are working with the appropriate authorities to investigate the situation,” a BHP spokeswoman said.

BHP declined to give further details, including what might have caused the incident and how long operations will be halted.

The mining giant exported 69 million tonnes of iron ore from Port Hedland in the three months to September.

The site of the derailment will need to be cleared of rolling stock and the track repaired before rail operations can resume.

While BHP’s Pilbara operations have had derailments in the past, none have been on this scale.

In 2015, a 25-wagon derailment shut down BHP’s railway operation for three days before traffic resumed.

According to a report released last month, the ATSB said the incident was caused by a broken rail, probably with a defect that could have been detected but was not. The report said that as a result, BHP accelerated the re-railing of more than 800km of track and improved the detection of cracks in rails.

In February last year, about 40 BHP ore wagons came off the rail line about 130km south of Port Hedland.

Rio Tinto has had derailments but never a runaway train.

In December 2015, 56 of its ore wagons derailed because of a small track misalignment.

The line was operational three days later.

In July this year, Rio delivered its first iron ore to port using a driverless train.

The mining giant expects to have full driverless rail operations by the end of the year.

BHP has so far opted against trying to introduce driverless operations across its Pilbara network.