Foxtons has been hit by an online hack attack, but insists that it did not result in the personal details of thousands of customers, including landlords, being compromised, which meant that there was no need to notify customers that their data may be at risk.

The estate agency suffered a breach to its systems that forced it to shut its MyFoxtons customer portal last Friday, an incident which the London-based firm reported to the Information Commissioner’s Office and the National Cyber Crime Agency.

However, the company contacted EYE this morning to make it clear that there was no requirement to write to customers of its online service to warn them of the data breach, as no personal details, including email addresses, usernames and passwords, were accessed by the online hacker.

A spokesman said: “Foxtons has been subject to a limited malware virus on a small part of the business. It appears many other businesses and organisations have been affected and this was not a targeted attack on Foxtons.

“We have effective systems in place and took quick action to contain the incident and minimise disruption to our customers. Current investigations reveal no sensitive data has been compromised.”

Despite Foxtons confirming that no “sensitive data” had been stolen, some customers have expressed anger at the firm’s failure to inform them of the breach and said Foxtons had instead told them its systems were undergoing an upgrade.

One customer told the i newspaper: “I am concerned whether data has been stolen. It’s scandalous there was a hack and they just kept quiet about it.”

In 2013, the group was forced to investigate whether hackers had stolen the details of almost 10,000 property hunters following an anonymous leak on a hacking website.

The company at the time did write to customers of its online service MyFoxtons to warn them of the data breach.