Robots and computers could replace almost 250,000 public sector workers over the next 15 years, improving efficiency and saving billions of pounds, according to a new report.

The Reform thinktank said use of websites and artificially intelligent "chat bots" would remove the need for 130,000 Whitehall administrators, around 90% of the total, by 2030, saving £2.6 billion a year.

A further 90,000 NHS administrative posts and 24,000 GP receptionists could be subjected to automation in a similar way, with savings of more than £1.7 billion.

Even roles normally associated with human practitioners could fall victim to the march of the machines, with around 30% of nursing activities, such as collecting information and administering non-intravenous medication, suitable for automation.

Doctors also would not be immune, with computers already proving more effective at diagnosing lung cancer, while robots are outperforming human surgeons in routine procedures.

The report also highlights the scope for increased automation in policing through crowd-monitoring drones and facial recognition technology, although it recognises the concerns involved in holding people's images.

It argues that public services should become more flexible by embracing an Uber-style "gig" economy with workers supporting themselves through a variety of flexible jobs acquired through online platforms.

Such "contingent labour" platforms, it says, could suit hospitals and schools as an alternative to traditional agency models, as well as organisations which experience seasonal peaks in demand such as HMRC at the end of the tax year.

Alexander Hitchcock, the report's co-author, said: "Such a rapid advance in the use of technology may seem controversial, and any job losses must be handled sensitively.