Ukraine's largest mobile operator, Kyivstar, has identified the issue that caused a disruption in voice and mobile internet services across several regions, the company's press service reported on Thursday.

"Today, September 19, certain Kyivstar network services experienced a technical outage. Our specialists quickly located the problem and are now working on restoring full service. The network restoration efforts are ongoing," the company stated in response to an inquiry from Interfax-Ukraine.

The company added that some difficulties with voice and internet services may still occur in Ukraine's eastern and northern regions but should be resolved within the next 30 minutes.

Earlier, Kyivstar customers reported problems with voice calls and mobile internet, particularly in Chernihiv, Sumy, Cherkasy, Kirovohrad, Zaporizhia, Dnipropetrovsk, Donetsk, Kharkiv, and Poltava regions.