WPP chief executive Sir Martin Sorrell has revealed the extent of the cyber-attack experienced by the company earlier this year cost the company between £10m - £15m during the 10-day period that the company was affected.

Speaking openly about the reaction to the hack, which took place in June, Sir Martin revealed that not all of the world’s largest advertising agency network was affected and that the company was now set to spend millions incrementally each year to attempt to avoid a repeat in the future, although admitted that the company still “had issues.”

“You can never be comfortable because you can never be 100% certain. It’s a bit like consumer brand safety, you can’t be certain that you aren’t have a problem on Google or Facebook but it means that you reduce the possibility of something going wrong” he told The Drum, and also revealed that the company will spend another £10m - £15m incrementally each year on preventative measures.

While he was not open on the processes that were being installed by WPP, in order not to offer more assistance to future attacks, Sorrell also praised the work of those internally who worked 24/7 to overcome the issue, as well as partners IBM and the networks clients for their support.

“People in high pressure situations responded magnificently,” he stated.