MTN Group, Africa’s largest mobile operator, said on Thursday it suffered a cybersecurity breach that exposed personal data of some customers in certain markets, but its core networks, billing systems, and financial platforms remain secure.

An unidentified third party claimed to have accessed parts of MTN’s systems, the company said in a statement posted on its website.

While the scope of the breach is still under investigation, MTN reassured stakeholders that there is no indication that customer accounts or digital wallets were directly compromised.

“No evidence of compromise to any of our critical infrastructure, core MTN platforms, or services,” MTN stated, adding that its “core network, billing systems, and financial services infrastructure remain secure and fully operational.”

The Johannesburg-based telecom giant, which serves 280 million customers across 19 countries, has notified the South African Police Service and the Hawks, a specialised crime unit, and is coordinating with authorities in affected markets.

MTN is also reaching out to impacted customers to meet local regulatory requirements.