In a speech at the Labour party conference in Liverpool on Wednesday, Mr Ashworth told delegates: 'For me, patients will always come first. As your health secretary I would never abandon my responsibilities to patient care and safety.
'And by the way, I certainly wouldn't be pushing an untested private health app like this new health secretary is doing. It is so irresponsible. Because we know privatisation puts patient care at risk.'
The Labour shadow health secretary's rebuke follows criticism from the BMA and RCGP over Mr Hancock's support for GP at Hand - with warnings that a national rollout of the service could trigger 'significant destabilisation' of general practice and drive up already soaring demand.
Mr Hancock - who has personally registered as a patient with GP at Hand - has repeatedly backed a wider rollout of the service since taking over as health and social care secretary in July.
In his first major speech in the post he praised GP at Hand and called for similar technology to be 'available to all', going one step further this month by calling for GP at Hand itself to be rolled out nationwide.
Speaking at an event hosted by Babylon, the private company behind GP at Hand, Mr Hancock said on 13 September: 'It works brilliantly for so many patients and goes with the grain of how people access modern services. Where a new service challenges the system, the right response isn’t to reject the new service but to change the system.’
RCGP vice chair of external affairs Professor Martin Marshall last week warned the health and social care secretary against 'deaf enthusiasm' for so-called disruptive technology. He called for 'rigorous evaluation' of new technology before it was introduced, and warned that new tools should be integrated with existing general practice rather than brought in to compete with it.
The BMA has warned that a wider rollout of the service threatens to undermine the funding model behind general practice, accusing GP at Hand of 'cherry picking' young patients by excluding complex patients from registering.
A DHSC spokesperson said: 'Technology has the potential to transform care for patients – that’s why we are encouraging innovation from right across the tech sector to work with the NHS, so clinicians have more time to spend caring for patients and every pound spent goes further.'
A spokesperson for GP at Hand said the service was 'a fully-fledged NHS practice' that had been thoroughly tested internally and externally.
'Babylon is making its technology and GPs available to any NHS practice up and down the country,' the spokesperson said. 'The debate should be whether it is safe or effective to carry out NHS care without using the latest technology.'