GPs are cutting back on handing out antibiotics after being warned about over-prescribing them, research shows.

A study by the Behavioural Insights Team (BIT) said prescriptions were reduced by just over 3% (73,406) between 2014 and 2015 after it sent letters to 800 GP practices, telling them that other practices were recommending antibiotics in fewer cases.

Researchers say the aim of the study is to crack down on the growth of antimicrobial resistance (AMR), which they describe as "one of the major health challenges of our time."

AMR will result in 10 million deaths a year worldwide by 2050, according to national figures.

The study is part of a wide-ranging investigation by BIT - the body that studies patterns of public behaviour in a bid to make public services more efficient - that also looks at education, employment and energy.

Formerly known as Nudge, it was run completely from 10 Downing Street, but has been part owned by its employees and Nesta charity since 2014.

As well as conducting its own studies, the report outlined plans to address other key issues within health services, including overspending in the NHS and unnecessary attendances at A&E departments.

BIT tried a system of writing to patients in response to a 2013 NHS England report stating that 40% of A&E patients are discharged without requiring treatment, and a National Audit Office report claiming that around a fifth of admissions are for conditions that could be managed by other care services.

It sent letters between January and September 2015 to discharged A&E patients with information about alternative care options.

But a follow-up survey after February this year showed the information made no difference to A&E attendance rates.

Researchers said this data is "one of the first pieces of rigorous evidence on how feedback affects A&E attendance behaviour," and are planning other studies.

BIT will trial a new project with King's College aimed at promoting cheaper, better quality products to NHS staff to help them make more efficient choices.

This follows a review by Lord Carter that said the NHS could save £1 billion of its £9 billion spending budget by looking into more modern practises and systems.