The 106-page document, from the Royal Australia and New Zealand College Of Obstetricians and Gynaecologists, signals an escalation of the specialists' opposition to an expanded role for midwives in managing births - which the Federal Health Minister, Nicola Roxon, has indicated she views sympathetically.

According to the submission to the federal health department review, "dividing all pregnant women into either 'high' or 'low' risk is not possible and any attempt to do so creates more problems than it solves" - a reference to the suggestion that midwives take responsibility for more women without anticipated medical problems.

The obstetricians' submission is one of more than 900 received by the review, the bulk of them from individual women concerned that their own experience of birth involved excessive medical intervention.

Nearly half the submissions were published online yesterday, following new national statistics from the Australian Institute of Health and Welfare that revealed the caesarean birth rate increased to 31 per cent in 2006, compared to the OECD average of 22 per cent.

The college defended Australia's surgical birth rate, saying it was on a par with that of the US and only fractionally higher than Britain. This was to be expected because countries with a higher population density had "the luxury of nearly all hospital births occurring in facilities with the immediate availability of caesarean section", while Australian doctors in more isolated areas had to pre-empt possible difficulties and transfer women to larger centres for a caesarean.

But in an individual submission, David Ellwood, professor of obstetrics and gynaecology at the Australian National University, said he was concerned at the rising caesarean rate and that surgical birth rates in private hospitals were "inappropriately high".