Patients have been delayed inside ambulances for at least 30 minutes almost 1.5m times over the past three years due to waiting for hospital handovers, information provided to Labour has shown, with the party saying it was “damning evidence” of a crisis in the NHS.

In more than 280,000 of these cases, people were delayed for more than 60 minutes, according to figures provided by freedom of information requests to ambulance trusts in England.

NHS guidance says patients in ambulances should be passed into the care of hospital staff within 15 minutes.

Labour said the numbers were almost certain to be underestimates of the true picture, as one of the 10 ambulance trusts, Yorkshire, did not respond to the information request and two others, South Central and West Midlands, had no or incomplete figures.

Releasing the statistics ahead of a rally focused on the NHS in Leeds on Saturday, Labour said that in the 2018/19 year, 503,887 patients waited at least 30 minutes, with 79,352 of these being delayed in the ambulance for an hour or more.

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Over the last three financial years, 1,499,053 people were delayed more than 30 minutes, with 280,299 waiting an hour or longer. Such waits are often caused by a lack of capacity inside the relevant accident and emergency department.

Jonathan Ashworth, the shadow health secretary, said: “This is damning evidence of the crisis our NHS has been pushed into after a decade of cuts. Many of these patients will be elderly in desperate need yet they have been left waiting and waiting.

“It’s a disgrace and comes after cuts to 17,000 hospital beds under the Tories.

You can’t trust Boris Johnson with our NHS but you can trust Labour to deliver the standards of care patients deserve with our £40bn cash rescue plan.”

Labour is seeking to use NHS cuts as a major line of attack during the election. The announcement on the ambulance waits noted that an earlier freedom of information request showing that ambulance trusts in England spent £68m on private ambulances in 2018/19, up from £19.9m the year before.

On Wednesday, Jeremy Corbyn produced documents detailing UK-US trade talks, which the Labour leader said proved that the US was demanding access to the NHS and its markets for a post-Brexit deal. The government has rejected this as false.