Fishing tackle retailer Angling Direct PLC's (AIM:ANG) website was shut down over the entire weekend after unauthorised activity on the network was detected.
The website has been on a hiatus since the cyber security breach was noticed on Friday evening.
Angling said work has continues "round the clock" to bring the websites back online while reassuring customers that its 39 retail stores across the UK have remained open and continue to trade.
"The board has appointed external cyber security specialists whose investigations are underway to establish what happened,” the company said.
Many of Angling’s customers are concerned that in the ongoing three-day breach it is possible that vast amounts of customer data had been retrieved and could have put their personal details in the hands of hackers.
The company’s shares were down 5% to 65.5p on the morning of 8 November.
The company said it does not anticipate the security breach incident to impact underlying trading but is wary of potential additional cost exposure.
The attack also helped gain access to a handful of the company’s social media accounts.