Retired family doctors are being urged to come back to work as part of a project aimed at boosting recruitment and retention after new figures showed a fall in the GP workforce.

A survey in 2015 showed Scotland had the equivalent of 3,645 full-time GPs, down from 3,735 in 2013, with Labour accusing the Scottish Government of having brought about "the biggest crisis in family doctors for a generation".

The drop comes at a time when there is an increasing demand on GP services as a result of the ageing population and the shift to providing more medical care in the community.

GP vacancies are on the rise, according to NHS figures, with the report also showing out-of-hours services are "reliant on a relatively small number of GPs" to provide care in the evenings and weekends.

The Scottish Government is spending more than £2 million on "innovative and exciting" projects aimed at tackling workforce problems, including the development of a locum pool of retired GPs in the Lothians area.

The funding comes from the government's £85 million Primary Care Fund, with Health Secretary Shona Robison saying: "This investment will help to get these innovative and exciting projects off the ground - allowing frontline staff to test new ways of working and new models of care that can be rolled out nationally if they are a success.

"It demonstrates our commitment to supporting and developing local GP and primary care services, and working with our partners to do so. We have also pledged to increase the number of GPs working in our NHS."

Ms Robison accepted there "still remain challenges in recruiting and retaining doctors to work in general practice".

While she said Scotland continues to have the highest number of GPs per patient in the UK, Ms Robison stressed: "We still need to act now to redesign the way care is provided in the community to ensure these services are sustainable in the future."

The 2015 national primary care workforce survey showed a fall in the number of GPs working full-time from 51% of the workforce in 2013 to 43% in 2015.

Among male GPs, who are most likely to work full-time, nearly half are aged 50 or over.

Nine out of 10 practices surveyed reported having to use locums and temporary staff to fill in when doctors are either sick or on holiday - but 60% of practices said they were regularly unable to recruit locums for unplanned absences.

While a quarter of GPs did some out-of-hours work, the service was reliant on a small number of staff covering a "notable proportion of the hours worked", the report said.

Labour health spokesman Anas Sarwar blasted: "The SNP government in Edinburgh has created the biggest crisis in family doctors for a generation, with over £1 billion cut from primary care.

"We can't just have another promise to train more GPs at some point in the future. We have a crisis in GP services now that the SNP Health Secretary must recognise and address."

Donald Cameron, the Tory health spokesman, accused the Government of having "ignored" warnings about the "dwindling number of GPs".

He added: "As a result, patients are paying the price, appointments are hard to come by and those GPs left are feeling overstretched."

Liberal Democrat MSP Alex Cole-Hamilton said: "The prescription for primary care is clear - additional funding in GP services and support for doctors, nurses and practice staff who are often our first port of call when we are unwell."

Dr Alan McDevitt, chair of the BMA's Scottish GP Committee and a practising GP in Clydebank, West Dunbartonshire, said: "This survey illustrates the extent of the problems that are currently facing primary care.

"GPs are choosing to leave the profession and those that remain are facing an increasingly unmanageable workload.

"Without significant funding invested specifically in general practice recruitment and retention, the situation will only get worse."

Dr McDevitt added that the additional cash from the Scottish Government "is nowhere near sufficient to make an impact on the problems facing general practice".

He said the figures "show how serious the recruitment and retention issues in general practice have become and it is essential that practices receive the support they so urgently need to prevent them from reaching crisis point".