Junior doctors at three north London hospitals are taking part in five days of strike action.
The strikes, impacting all three hospitals run by the Royal Free London NHS Foundation Trust, started at 7am on Thursday, June 27 and will continue until 7am on Tuesday, July 2.
Previous industrial action took place over four days in February and for six days in early January.
The strike action will affect the Royal Free Hospital in Hampstead, Barnet Hospital, and Chase Farm Hospital in Enfield.
While emergency care and acute services will be prioritised for those needing urgent treatment, individuals are encouraged to use alternative non-hospital services for treatment and advice during the strike.
These include the NHS 111 phone service, GP practices, walk-in centres, and pharmacies.
Patients due to have outpatient appointments or procedures will be contacted directly if there is a need to reschedule.
However they should attend as normal if they are not contacted.
The Royal Free London, founded in 1828, serves more than 1.6 million people across 70 sites in north London and Hertfordshire and is one of the UK's biggest providers of cancer care.
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