Trine Lind, of the Norwegian Radium Hospital, says, "The material was fabricated. We are shocked. This is the worst thing that could happen in a research institution like ours."
Jon Sudbo, 44, invented patients and case histories for a study of oral cancer published in the Lancet British medical journal in October 2005.
Norwegian daily, Dagbladet, says 250 of the 908 people "sampled" shared the same birthday.
Lind says Sudho has not commented on the charges but did admit to falsifying data.
The hospital has set up a commission to investigate why Sudho falsified data for the article.
