Hounslow Councillor Barbara Harris, who was appointed chairman of the adult health and social care scrutiny panel last month, is so concerned she has written to NHS London and the Strategic Health Authority.
West Mid bosses predicted earlier this month that they will rack up a £10m deficit this year, leaving it £27m in the red. The hospital, in Twickenham Road, Isleworth, is one of 11 'financially challenged' trusts working with NHS to wipe out its debts using money from the capital's better-off trusts.
Cllr Harris said: "The current level of debt in particular is extremely worrying and I have to admit it is difficult to fully understand what the consequences of this debt have been on the quality of hospital care that patients receive.
"We know that at the moment the quality of care you receive often depends on where you live in London.
"This is not right - all hospitals and health services should be delivering a consistent quality of care to the public, regardless of where they live in London or who they are."
A spokesman for West Mid welcomed Cllr Harris to her new role and said the hospital's staff were looking forward to working with her and were fully committed to responding to any concerns brought to their attention by the panel.
Cllr Harris wants to encourage more patients to come forward to the panel with their experiences - good or bad - to identify any problems at the hospital and improve services.
"I want to make sure that residents continue to come forward and be honest about what they think," she said.
"The hospital relies on patient feedback to improve its services and, as a scrutiny councillor, I want to use residents' feedback to ask questions about services and make sure that any problems that are identified are dealt with quickly, so that services improve for all patients."
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