The job losses, affecting cancer services, cardiology and paediatrics, are necessary to achieve savings of pounds 16m that are still required by the opening of the hospital, which is being touted as the Government's flagship NHS development.
An internal report to Riverside Health Authority says there will be matching cuts in the numbers of junior doctors, with 50 nursing posts and 10 in management also to go.
The authority's hospitals have been hit by falling contracts in the NHS internal market, the paper says.
The original proposal for the Chelsea and Westminster - which is now accepting out-patients and will be fully operational by April - required pounds 23m savings from rationalisation, the paper says.
Because the NHS reforms have 'fundamentally altered the financial regime of the service', pounds 16m is still outstanding. The internal market has led to a pounds 6.5m loss in income from other health authorities in the current year, and a further pounds 10m next year.
The development of the Chelsea and Westminster has been accompanied by a reduction in the number of hospital sites - from six to two - providing acute services in the area. Posts were reduced among all staff 'with the exception, to a large extent, of medical staff', the paper says.
'The number of consultant sessions has not reduced in line with the cumulative effect of productivity and efficiency gains over the years and must now be critically examined,' it says. The paper proposes cuts to produce pounds 1.2m savings in the current financial year.
A spokesman for Riverside Health Authority confirmed the internal report and said details were being circulated among staff.
Brian Sedgemore, Labour MP for Hackney South, to whom the Riverside document was passed, said yesterday it showed 'chaos and cuts resulting from the internal market and the opening of the Westminster and Chelsea'.