T-Mobile confirms it has been the victim of a cyber attack

US mobile phone operator T-Mobile confirmed on Monday that it had been the victim of a cyber attack, but declined to provide details on its scope or the number of customers who may have been affected.

In a statement, T-Mobile said there had been "unauthorised access" to company data, but said it had not yet verified that personal customer data had been leaked.

The company added that it is working with law enforcement to find out what happened, but warned that the investigation may take time although it is working with the "highest degree of urgency".

On Sunday, hackers told technology portal Motherboard that they had accessed the personal data of 100 million people through T-Mobile's servers.

According to Motherboard, the cybercriminals are demanding a ransom of six bitcoins (about $270,000) in exchange for the data, which allegedly includes names, addresses, driver's licence numbers and other personal information.

T-Mobile has so far declined to confirm whether the hackers are asking for a ransom, nor has it detailed what data they may have accessed.

This latest cyberattack comes after a year full of such attacks, such as the one last May against the main US oil pipeline, Colonial, which caused fuel shortages in several eastern states, including North Carolina, Virginia and Washington DC, the worst affected.

In May, JBS, the world's largest meat processor, suffered another cyberattack, and in July there was another offensive against Kaseya, a software company that provides services to more than 40,000 organisations worldwide.