East Japan Railway says it will gradually resume operations of linked bullet trains from Friday after a decoupling incident last week led to a suspension.



JR East told reporters on Tuesday that service will be fully restored on Saturday. The railway operator also provided some details of the accidental decoupling on the Tohoku Shinkansen line last Thursday.



The trains -- known as Hayabusa and Komachi -- were traveling in Tokyo when the coupler became detached. JR East responded by temporarily halting all its coupled Shinkansen operations.



The company said an inspection right after the incident found that the coupler on the Komachi train had repeatedly moved in a way that suggested detachment.



The railway operator said a movement of this kind had never been confirmed before. The company said an electrical abnormality is one potential cause, but the reason hasn't been confirmed.



The company says it will fix the connecting part with metal fittings so that the train remains coupled even if an electric abnormality occurs.



The train operator says it will conduct a test run to see if the measure will work before it will resume coupled operations of the bullet trains from Friday.



Officials of the Japan Transport Safety Board are conducting an investigation to identify the cause of the decoupling. Specifically, they have been interviewing train crews and checking train cars.