Kingston Hospital has been shifting patients on to private lists to meet Government targets on waiting times.
Exactly 76 patients were sent to privately-run independent treatment centres during April mainly for eye treatment.
The hospital spent £66,000 to ensure no patients waited more than 18 weeks for treatment after being referred by their GP.
Geoff Martin of campaign group London Health Emergency said: "Money is being diverted to the private sector just to keep up with Government-imposed targets.
"We should have the capacity to be able to work within the NHS without having to resort to these costly manoeuvres.
"This is another opportunity for the private hospital list to make a fast buck."
The spend, largely on ophthalmology, contributed to a £200,000 overspend for the Trust in the first month of the financial year.
Kingston and Surbiton MP Edward Davey believed there may be other consequences of the struggle to meet targets, but played down the cost.
He said: "I am quite surprised it is so little. It is the perverse effect of trying to make 18 weeks.
"I have a strong suspicion that there will be consultants and specialists out there who are fed up of these centrally imposed targets that force them to treat patients in ways they would not choose to.
"The consultants who work evenings and weekends don't have the time to do the follow up appointments."
Kingston Hospital said its consultants had worked evenings and weekends to meet the "very challenging" target which it must meet by December 2008.
"However, on occasions, we have referred some patients to our independent sector partners for treatment because we reached our capacity to treat our patients in-house.
"We would stress, however, that this is a short term arrangement, and it has been agreed with our local PCT partners.
"We are reviewing our capacity and redesigning our services to ensure that we can treat all our patients within 18 weeks, in-house, in the longer term.
"As a general principle, we are charged NHS tariff rates for treatment carried out on our behalf by independent sector partners."
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