The massive earthquake that hit Japan's northeastern region has caused telephone traffic to surge between South Korea and its neighbor that effectively made placing calls impossible, the country's largest telephone operator said Friday.

   KT Corp. said that from 5 p.m. to 6 p.m. cellular and landline phone traffic shot up 91 times and 41 times, respectively, compared to normal traffic.

   Calls were made mostly by people in South Korea trying to contact relatives and friends in Japan to ask if they were safe.

   There were 69,308 calls made using cell phones and 21,418 calls on fixed landline phones during the time period.

   "The extent of phone traffic made it hard to connect, especially since there seem to have been problems taking place in Japanese telecommunications services at the time," the corporation said.

   It said there were no problems with international calls going from South Korea to Japan, but calls were not going through inside Japan.

   KT added that its staff have been placed on emergency standby in case of unexpected developments.

   The telephone operator, meanwhile, said that the massive quake that took place off Japan's northeastern coast disrupted one of 10 under-ocean international telephone lines linking the island nation and the United States. The line that has been affected is used by four local communications companies, including KT, and could result in minor problems for phone calls to North America.