Dec 15 (Reuters) - ‌Britain's telecom and media regulator Ofcom said on Monday ‍it had ‌launched investigations into top mobile and broadband services providers BT Group ⁠and Three following summer outages ‌that disrupted mobile services nationwide.

The outages affected thousands of customers across BT’s EE network and Three UK, causing widespread disruption in the UK to ⁠call services and preventing users from making or receiving calls to other networks, including ​emergency services.

The regulator said BT's software issue from ‌July 24 to 25 affected ⁠EE and BT customers, while Three had notified Ofcom about a separate incident on June 25 that similarly affected call services.

Ofcom ​said on Monday it would assess whether the companies had failed to comply with requirements to take appropriate measures to prevent network failures and mitigate their impact when they occur.

"We will co-operate ​fully with ‍Ofcom throughout the investigation ​and apologise again for any issues caused by this incident," a spokesperson for BT, Britain’s largest broadband provider, said in an emailed statement.

The company is facing line losses amid intensifying competition in the consumer market while also working to expand its fibre network to ⁠reach 25 million premises by December 2026.

Meanwhile, Vodafone and CK Hutchison completed the $19 billion merger of ​their UK operations earlier this year, creating VodafoneThree, the country's largest mobile operator.

A spokesperson for VodafoneThree said it has engaged with Ofcom since the outage and will continue to ‌also co-operate with the investigation.

(Reporting by Raechel Thankam Job and DhanushVignesh Babu in Bengaluru; Editing by Mrigank Dhaniwala, Subhranshu Sahu and Susan Fenton)