The recent cyber hack on TalkTalk's website could cost the company up to £35 million in one-off costs, the telecoms giant has said.

TalkTalk's shares were up 10% after the announcement, but still remain nearly 25% down on where they were before the attack. More than 150,000 customers' data was stolen and around 15,000 had their bank account information stolen.

TalkTalk said it would give free upgrades to customers affected, and it would not force those who have suffered financially to pay a cancellation fee if they wanted to leave the company.

Speaking to the BBC, Ms Harding said: "The estimated one-off costs are between £30m and £35m - that's covering the response to the incident, the incremental calls into our call centres, obviously the additional IT and technology costs, and then the fact that over the last three weeks until yesterday our online sales sites have been down, so there will be lost revenue as a result."

Ms Harding also said it was too early to tell what the long-term impact of the attack would be.