TOKYO, July 14 (UPI) -- A survey of Japanese fertility clinics found about 30 percent of information on sperm donors has been destroyed, officials said.

Under the Medical Practitioners Law, such clinics are required to keep donor records for five years, The Yomiuri Shimbun reported.

However, the Japan Society of Obstetrics and Gynecology advises fertility clinics keep records a longer period of time, as children conceived via artificial insemination by a donor, or AID, may try to find their biological fathers when they are older.

A survey conducted by the newspaper in June of 23 registered medical institutions found 12 clinics that provide AID said they keep all clinical records of the couples who have done the procedure, including information on the sperm donors. Six other institutions said they do not keep clinical records that contained information to identify donors. One clinic said it disposes of the records, but keeps other relevant documents. Four clinics surveyed said they did not do AID.

Japan does not have a law that regulates reproductive medical treatments such as artificial insemination performed by third parties,which mean children born through AID have no legal right to find out who their biological father is.

Experts say there is a need to create legislation that helps these children.

"In the future, authorities will have to grant children the right to know who their biological parents are," said Yasunori Yoshimura, a professor of the Obstetrics and Gynecology Department at Keio University. "Discussions are needed to create a public body to manage relevant information in an integrated fashion."