Thyssen Krupp AG (www.thyssenkrupp.com/en) has reported that technical trade secrets were stolen in cyber attacks last year, after the German industrial conglomerate became “the target of a massive cyber-attack”.

Breaches discovered by the group’s internal security team in April were traced back to February. Thyssen Krupp, one of the world’s largest steel makers, attributed the breaches to attackers in South East Asia engaged in what it said were “organised and highly professional hacker activities”.

German business magazine Wirtschafts Woche reported that the attacks hit sites in Europe, India, Argentina and the USA run by the Industrial Solutions division, which builds large production plants.

The Hagen Hohenlimburg specialty steel mill in western Germany was also targeted, the magazine added. The company declined to identify specific locations that were affected or why it had not previously disclosed the attack. It said it could not estimate the scale of the intellectual-property losses.

A spokesman for the company, which has been looking to merge its European steel operations with Indian-owned Tata Steel to combat over-capacity in the sector, said: “No breaches were found at our marine-systems unit, which produces military submarines and war-ships. The infected computer systems have been cleansed and are now subject to constant monitoring against further cyber-attacks.”

Wirtschafts Woche said that a 2014 cyber-attack caused “massive” physical damage to a German steel plant and prevented the mill’s blast furnace from shutting down properly. It gave no further technical details, and the location of the plant remains unknown.