Thousands of patients could be denied medical care later this week as doctors strike for the first time in 40 years.
The Department of Health has warned that up to 200,000 outpatient appointments, 58,000 diagnostic tests and 30,000 operations could be cancelled on June 21.
More than one million GP appointments could also be postponed as a result of the protest over government pension plans .
More than 100,000 members of the British Medical Association voted overwhelmingly earlier this month to provide only emergency care during the day of action.
The Government wants new doctors to work three years longer, until they are 68, and contribute more towards their pension. They would retire on £68,000 a year.
Health Secretary Andrew Lansley said the deal was fair, and that doctors would still enjoy pensions that are worth more than twice the average national salary.
But doctors say the Government is ripping up a deal agreed four years ago that ensured their pension scheme was affordable.
It is still unclear how patients will be affected by the day of action.
Some hospitals say it will be "business as usual", with doctors taking on the work of striking colleagues.
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