The Harvard Law School Legal Services Center sent out a letter to its clients on Tuesday announcing that a tape with sensitive information about over 21,000 clients had been lost for over a month.

The lost tape contains clients’ Social Security numbers, financial information, contact data, and other personal details.

It is one of six weekly back-up tapes normally used at the center’s Jamaica Plain office. The tape was last seen on September 23rd, when it was collected from the Legal Services Center by the Law School’s information technology service. It was supposed to be taken to the HLS campus where it would be backed up, according to Robert L. J. London ’79, the Law School’s acting assistant dean for communications.

“We do not know at what point, how, or where it was probably lost,” London said.

He said that the original information remains secure in the center’s computerized data storage system, and added that it is “highly unlikely” that the tape will be put to misuse.

“While we regret this, we really believe that the risk of access to this data is extremely low,” London said. “We want to emphasize that the data on the tape was password-protected and anyone trying to gain access to it would have to have specialized equipment and skills.”

He said that the Legal Services Center is taking precautionary measures in case the information is compromised. The Law School has notified the Massachusetts Office of the Attorney General, following the guidelines of the Massachusetts Privacy Statute, according to London.

London said that the Legal Service Center is offering its affected clients a free credit monitoring service and a security freeze on their credit reports, and added that the center would implement preventative measures to protect the tapes in the future.

The Legal Services Center is a general practice law firm that provides practical training experience for Law School students and legal counsel to clients from the community, many of whom are poor. It currently represents around 1,200 clients in the area, according to its Web site.