The NHS should email patients rather than relying on letters - which can mean "the difference between life and death" if lost, the Health Secretary is expected to say.

Matt Hancock will say email should be the default way of communicating for the health service by 2021, The Times has reported.

Mr Hancock will tell an NHS England conference: "Having to deal with outdated technology is hugely frustrating for staff and patients alike - and in many cases, downright dangerous.

"A letter lost in the post could be the difference between life and death."

Mr Hancock is expected to say that email systems are secure enough to protect patient data, and could prevent patients from waiting days for communication from their doctor.

He will add: "Today's guidance confirms there is no reason why a doctor cannot email a patient confidentially, for example, with their test results or a prescription, rather than make them wait days for a letter or ask them to come into the surgery.

"The rest of the world runs on email, and the NHS should too."

The announcement has been met with mixed reaction from professionals.

Carrie MacEwen, chairwoman of the Academy of Medical Royal Colleges, told The Times: "We entirely agree that in the 21st century the NHS should be using email and texts to communicate with patients wherever possible."

However, Helen Stokes-Lampard, the chairwoman of the Royal College of GPs, told the newspaper existing "clunky" NHS IT systems could hamper efforts to make changes quickly and safely.