Australia’s OneSteel says its Whyalla blast furnace cannot be restarted and it may take four weeks until it returns to normal operating levels.

The Whyalla plant in South Australia was closed on Sunday, 11 April , following an incident that released hot material.

OneSteel said that repairs had been completed to the blast furnace but it could not be restarted.

"Following stoppages over the weekend the company completed the required repairs to the Whyalla blast furnace," OneSteel said in a statement.

"But as of this morning has been unable to recommence operations due to difficulty in re-establishing connections between the blast furnace tap holes and tuyeres."

The steel maker said OneSteel now expected it would take about four weeks to return the blast furnace to normal operating levels.

But it added it only expects minimal impact on customer demand due to available EAF capacity.

"At this time the company does not believe the interruption will have a material impact on its earnings for the second half of this financial year."