STOCKHOLM (Reuters) - Mobile network equipment group Ericsson ERICb.ST said on Thursday it had identified an issue in certain nodes in the core network resulting in network disturbances for some customers.

It said in a statement that the faulty software that caused these issues was being decommissioned.

Ericsson had said earlier on Thursday it was working with mobile companies in Britain and Japan to restore full service to millions of customers hit by outages caused by a software glitch in the Swedish company’s equipment.

Ericsson customers affected were using two specific software versions of the node “Serving GPRS Support Node - Mobility Management Entity” (SGSN-MME).

“An initial root cause analysis indicates that the main issue was an expired certificate in the software versions installed with these customers,” it said.

O2 TEF.MC, Britain's second biggest network, and Japan's Softbank 9984.T reported network outages on Thursday, leaving many customers unable to access internet services.