The owner of high-end fashion brands Hobbs, Whistles and Phase Eight says it is investigating a cyber-security incident.

According to TFG London - the UK arm of retail conglomerate The Foschini Group - it identified an incident on Sunday affecting some IT systems and "specifically impacting our Phase Eight, Hobbs, and Whistles brands".

"We are actively investigating and working with external cyber security specialists," the company told BBC News in a statement.

Meanwhile, H&M is investigating a separate claim that it was attacked by a notorious hacking group.

TFG said its brands' stores are operating as normal but some website capabilities may be unavailable, adding "we apologise for any disruption and will provide additional updates to our customers as appropriate".

The retail group reportedly told customers in an email that it did not believe customers' payment information had been affected by the incident.

"As our investigation continues, we will be working to identify if any sensitive information related to our customers was impacted," it said.

The email, seen by news service PA, also said that those whose personal information had been impacted would be informed directly.

"We do not believe it is necessary to change your account information at this time," it added.

Beverley Griffiths, senior lecturer in security and resilience at Bucks New University told PA that this was "a clear sign that major brands are firmly in the crosshairs of cyber attackers".

Fashion giants ranging from Adidas to Alexander McQueen have been targeted by cyber-criminals seeking to extort money by threatening to release customer data unless they are paid a ransom.

"No organisation is immune, so the real test of resilience is how quickly a business can detect an incident, respond and recover while keeping its customers informed," Griffiths said - adding customers should stay "vigilant" and wary of suspicious messages.

On Monday, it was also reported that fashion giant H&M was investigating claims of a hack by a cyber-criminal group called ShinyHunters.

The hackers have been previously linked to high-profile attacks including targeting the FBI, Rockstar Games and Ticketmaster.

"We are aware of information circulating online regarding a potential cyber security incident and are currently investigating the claims," H&M told BBC News in a statement.

"At this time, we have not found any indications that our data environment has been compromised." It also comes only a week after Asos customers were informed the online fashion and beauty retailer had been hacked by another group, via a push notification appearing on their phone screens.

Cyber-security experts told the BBC it was an unprecedented move for hackers to effectively transform an app notification system into a "ransom note".

It later emerged that hackers had obtained more detailed personal information belonging to Asos customers than the retailer initially suggested.

An update was issued to customers after BBC News told the retailer it had been contacted by cyber criminals who said the breach went beyond the "basic contact details" Asos previously said might have been accessed.