Edinburgh-based Tesco Bank said 9,000 customers were affected by the fraudulent transactions that hit the bank last weekend and that all customers affected were fully reimbursed by the evening of Tuesday November 8.
The total cost of refunding the customers is estimated to be £2.5 million.
Tesco Bank said normal service has resumed following the temporary suspension of online transactions from current accounts.
The bank said personal data was “not compromised” as a result of fraud that took place over the weekend and that online transactions had been suspended to prevent criminal activity.
Tesco Bank CEO Benny Higgins said: “Our first priority throughout this incident has been protecting and looking after our customers and we’d again like to apologise for the worry and inconvenience this issue has caused.
“We’ve now refunded all customer accounts affected by fraud and lifted the suspension of online debit transactions so that customers can use their accounts as normal.
“We’d also like to reassure our customers that none of their personal data has been compromised.”
Tesco Bank said it is continuing to work closely with the authorities and regulators in their criminal investigation of the incident.
Tesco Bank said it has 7.8 million customer accounts in the UK.
It said about 136,000 customers hold current accounts with the bank and 9,000 of these were identified as being victims of fraud.