The price of iron ore is again flirting with a six-year low after enduring a second consecutive red session overnight.

At the end of the latest offshore session, benchmark iron ore for immediate delivery to the port of Tianjin in China was trading at $US54.80 a tonne, down 1.3 per cent from its prior close of $US55.50 a tonne and within sight of the six-year low of $US54.20 reached at the beginning of the week.

Meanwhile, the metal bulletin price for iron ore delivered to the port of Qingdao, China, dropped 0.8 per cent to $US55.36.

As the price has continued to fall from levels above $US130 a tonne at the start of 2014 down to the $US50s, tension has been rising in the sector, with a clear gulf emerging between the giants and the rest of the market.

Heavyweights such as Vale, Rio Tinto and BHP Billiton have been happy to continue lifting production given they retain strong margins, but those with higher production costs are increasingly hitting out at the tactics, with Fortescue firing several broadsides this week.

The latest was from chairman Andrew Forrest who urged the majors to start "acting like grown-ups" and start cutting production. The comments caused a stir amid concerns they could promote collusion given he hinted a concerted effort from the industry to curb supply could lead prices back as high as $US90 a tonne.

Mr Forrest's views were slammed by Rio boss Sam Walsh on Thursday, who labelled his idea "hare-brained".

“I think the comments were absolute nonsense and I’m not sure Andrew had actually sought legal comment before making them,” he said.

“We have the wherewithal to be competitive with our mining; to try to artificially prop it up with some hare-brained scheme - that’s just physically not going to work.”

Gina Rinehart's Hancock Prospecting has largely stayed out of the increasingly bitter debate within the sector, with Ms Rinehart again striking a conciliatory tone overnight.

“If only we could do something about that falling iron ore price, well we can’t,” she said at the Mines and Money conference in Hong Kong.

“If Australia doesn’t supply iron ore, there are other countries who will, so we need to do what we can to cut Australia’s high costs.”