Payouts of more than $500,000 for doctors' mistakes, such as botched surgery or misdiagnosis, have almost doubled in recent years.

Data released by the Australian Institute for Health and Welfare shows the number of negligence claims against doctors that paid more than $500,000 jumped from 1.7% in 2004-05 to 2.8% the following year.

The institute has not released the actual number of claims in the report, which assessed negligence claims in both the public and private sectors. But according to research on the public sector only, there were 6922 claims lodged or in progress in the year ending June 2006.

Of all claims finalised in 2005-06, nearly two-thirds were settled for less than $100,000 and about half amounted to a payout of less than $10,000. No payment was made in 20% of cases.

Invasive procedures such as surgery were the single biggest cause of indemnity claims.