Millions of broadband Internet users across most of eastern Japan were unable to log on Tuesday evening after a problem at the country's largest broadband provider.

NTT East said 2.85 million customers lost Internet service at 6:44 p.m. (9:44 a.m. GMT) on Tuesday, the carrier said in a statement. The outage, the cause of which is still being investigated, lasted until 1:35 a.m. on Wednesday when the last of the affected customers was reconnected.

The outage is one of the largest in years and took out both PC Internet connections and IP telephone service across 14 of the 17 prefectures in which NTT East provides service. Customers in Tokyo and the surrounding prefectures of Kanagawa, Chiba and Saitama were not affected.

Of those affected, 1.2 million were on fiber-optic connections, 1.5 million on ADSL connections and 160,000 on ISDN lines, NTT East said.

NTT East said it fielded 11,300 calls from customers as a result of the problems.

The IDG News Service is a Network World affiliate.