An ABC investigation has revealed that Australia’s biggest online doctor’s appointment booking service funnelled hundreds of users private medical information to a law firm.

Secret documents obtained by ABC from plaintiff law giant Slater and Gordon reveal HealthEngine was passing on a daily list of prospective clients to the firm, based on personal medical information and part of a “referral partnership pilot” last year.

The documents showed that HealthEngine passed on details of an average of 200 clients a month to Slater and Gordon between March and August last year.