PRIME Minister David Cameron appealed to junior doctors to call off what he said was an unnecessary strike which would cause "real difficulties" for the state-run National Health Service.
The doctors are due to provide only emergency care for 24 hours from 0800 GMT on Tuesday, followed by a similar 48-hour stoppage starting January 26.
They make up around half of the medical workforce in Britain.
"This strike is not necessary, it will be damaging," Cameron said in a statement.
"We are doing everything we can to mitigate its effects but you can't have a strike on this scale in our NHS without there being some real difficulties for patients and potentially worse."
Junior doctors are qualified medical practitioners who are working while studying for postgraduate qualifications to become more senior consultants or general practitioners.
They are concerned about a new type of contract which the government says will improve healthcare at night and at weekends but medics say would drastically reduce their pay.
NHS England has said that 1,425 inpatient operations and procedures were being cancelled as a result of the strike along with 2,535 outpatient ones.
