The Metro staff, responding to a federal study that found the transit agency "vulnerable" to fraud, yesterday proposed hiring more auditors and modifying rules governing the acceptance of meals and other gifts by the system's employes.

The proposals sparked three hours of lengthy but inconclusive debate among members of a Metro board committee considering them.

The recommendations grew from an on-going investigation by the Inspector General of the U.S. Department of Transportation. After examining selected construction contracts, DOT investigators reported in April that they had found patterns of contractors entertaining Metro employes and consultants representing Metro and called its auditing procedures inadequate to protect against fraud.

According to the Metro staff committee looking into the gratuities question, some cases described in the federal study could not be verified. In addition to meals, employes are alleged to have accepted golf fees and fishing trips. But the staff report said the practice of accepting gratuities "is of sufficient magnitude to warrant concern."

The major steps proposed yesterday:

* Appointment of a special "auditor-general," who would have wide powers of investigation. Metro's internal audit staff, currently with 26 positions, would grow to 36 people.

* Rewriting of personnel rules to allow employes to accept meals and drinks that are consumed on the spot as well as low-cost promotional items such as calendars and rulers. Current rules bar acceptance of anything at all, which Page maintains is impractical and cannot be enforced.

* Changing contract language to allow Metro to enforce its gratuities rules on contractors and require them to produce records and other evidence in the event of an investigation.

* Creation of a board of ethics to monitor enforcement of standards and recommend changes as necessary.