The rise will amount to a 15%-20% jump in the price of structural sections which fell to £430-£450 a tonne during the summer.
British Steel first put the industry on notice in early December for a £30 a tonne New Year rise, blaming raw materials costs and a surge in global steel prices.
But this notice was suddenly withdrawn seven days later.
Now it has come back with a figure that is nearly treble the original planned increase, blaming unprecedented increases in raw materials costs.
One steelwork firm said: “Announcing an increase, then withdrawing it has just created confusion among clients and tier ones about which way prices are actually going.
“Then suddenly we are told to brace for a much bigger jump on all new orders placed in January.”
Another warned: “This is all too sudden and reactive, the industry needs more stable pricing, where suppliers manage spikes in input prices to level them out over the longer term.”