Labour have accused the Conservatives of lying about an alleged assault on an adviser to health secretary Matt Hancock in a bid to distract attention from the case of a four-year-old boy with suspected pneumonia left lying on an NHS hospital floor.

Shortly after Mr Hancock was dispatched to Leeds General Infirmary to discuss the case of Jack Williment-Barr, stories started emerging on social media about his aide supposedly being punched by a Labour activist among a group who had gathered outside to protest.

The story was shared on Twitter by senior TV correspondents, including the BBC’s Laura Kuenssberg, while blogger Guido Fawkes published what he said was an excerpt from a WhatsApp group showing that activists had been told they would be reimbursed for the cost of taking taxis to get to the hospital in time to heckle.

However, when footage later emerged of the incident, it appeared that the adviser walked into a protester’s hand from behind as he waved it. The adviser did not appear to be hurt and continued walking in the same direction without showing any signs of distress.

TV political editor Robert Peston apologised for having issued an account of the alleged incident, which he said had been briefed to him by “senior Tories”.

Shadow chancellor John McDonnell said: “Johnson and the Tories lie and they cheat to manipulate the media. A sick child treated on the floor of a hospital and they try divert attention with a dead cat lie story. Never has our politics sunk so low in our country since Johnson took over.”

Reports of the supposed incident came after the prime minister came under fire for refusing to look at a picture of four-year-old Jack as he took part in a TV interview. Mr Johnson was branded a “disgrace of a man” by Labour’s Jonathan Ashworth after he grabbed a TV reporter’s phone and put it in his pocket rather than looking at the picture on its screen.

Footage of the incident shows Mr Hancock being escorted to a car following his meeting with the hospital’s chief executive.

A group of around half a dozen people heckled the health secretary, with one woman shouting “shame on you”.

General election: Constituency profiles Show all 28 1 /28 General election: Constituency profiles General election: Constituency profiles Dunbartonshire East Constituency profile: Dunbartonshire East. See story POLITICS Election. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Milton Keynes South Constituency profile: Milton Keynes South. See story POLITICS Election MiltonKeynes. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Great Grimsby Constituency profile: Great Grimsby. See story POLITICS Election Grimsby. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Southampton Itchen Constituency profile: Southampton Itchen. See story POLITICS Election Southampton. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Truro & Falmouth Constituency profile: Truro & Falmouth. See story POLITICS Election Truro. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Brecon & Radnorshire Constituency profile: Brecon & Radnorshire. See story POLITICS Election Brecon. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Dudley North Constituency profile: Dudley North. See story POLITICS Election Dudley. Infographic by PA Graphics PA Graphics Press Association Images General election: Constituency profiles Norwich North Constituency profile: Norwich North See story POLITICS Election Norwich. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Fife North East Constituency profile: Fife North East. See story POLITICS Election Fife. Infographic PA Graphics Press Association Images General election: Constituency profiles St Ives Constituency profile: St Ives. See story POLITICS Election StIves. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Derbyshire North East Constituency profile: Derbyshire North East See story POLITICS Election Derbyshire. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Stirling Constituency profile: Stirling. See story POLITICS Election Stirling. Infographic by PA Graphics PA Graphics Press Association Images General election: Constituency profiles Sedgefield Constituency profile: Sedgefield. See story POLITICS Election Sedgefield. Infographic by PA Graphics Press Association Images General election: Constituency profiles St Albans Constituency profile: St Albans. See story POLITICS Election StAlbans. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Blackpool South Constituency profile: Blackpool South. See story POLITICS Election Blackpool. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Cambridge Constituency profile: Cambridge. See story POLITICS Election Cambridge. Infographic by PA Graphics Press Association Images General election: Constituency profiles Finchley & Golders Green Constituency profile: Finchley & Golders Green. See story POLITICS Election Finchley. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Bedford Constituency profile: Bedford. See story POLITICS Election Bedford. Infographic by PA Graphics PA Graphics Press Association Images General election: Constituency profiles Wells Constituency profile: Wells. See story POLITICS Election Wells. Infographic by PA Graphics PA Graphics Press Association Images General election: Constituency profiles Lancaster and Fleetwood Constituency profile: Lancaster and Fleetwood. See story POLITICS Election Lancaster. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Harlow Costituency profile: Harlow. See story POLITICS Election Harlow. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Hartlepool Constituency profile: Hartlepool. See story POLITICS Election Hartlepool. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Telford Constituency profile: Telford. See story POLITICS Election Telford. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Stockton South Constituency profile: Stockton South. See story POLITICS Election Stockton. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Uxbridge & South Ruislip Constituency profile: Uxbridge & South Ruislip. See story POLITICS Election Uxbridge.Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Ashfield Constituency profile: Ashfield. See story POLITICS Election Ashfield. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Moray Constituency profile: Moray. See story POLITICS Election Moray. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles South West Hertfordshire Constituency profile: South West Hertfordshire. See story POLITICS Election Tories Gauke. Infographic PA Graphics PA Graphics Press Association Images

There was no sign of violent behaviour or threats towards Mr Hancock, but a man in a hi-vis jacket pushing a bicycle approached his car to shout: “You are not welcome in this hospital. You are not welcome in this country.”

As the health secretary was driven away, the man with the bicycle turned to his adviser, who was standing next to him, and asked: “You look after these people? They have devastated our country. Absolutely devastated our country. There’s nothing left.”

The protestor then turned his back on the adviser, continuing to shout. He flung out his arm to point at Mr Hancock’s car, shouting “These people have devastated our country.” It was at this point that the adviser walked into his arm, apparently surprising the protestor, who told him: “I put my arm out. You walked into it.”

After reports starting circulating of an alleged punch, West Yorkshire Police issued a statement to say: “We are aware of information circulating on social media in relation to an alleged incident involving election campaigners at Leeds General Infirmary this afternoon.

“We are currently unaware of any reports of this nature but are seeking to verify.”

Confronted with Mr McDonnell’s allegation, a Conservative source did not dispute the suggestion that the party had spread inaccurate information about the incident, instead saying: “Disappointing that Labour are so determined to turn a four-year-old boy into a political football.”

The incident came after a day of controversy over young Jack’s experience in hospital, revealed on Sunday by the Yorkshire Evening Post, who interviewed his mother Sarah about how she was left to put coats on the floor for him to lie on.

Mr Johnson came under fire when he refused to look at a picture of the four-year-old during a TV interview, instead taking a smartphone with the image on its screen from a reporter’s hand and placing it in his pocket.

When ITV correspondent Joe Pike pointed out what he had done, the PM returned the phone, saying: “It’s a terrible, terrible photo and I apologise obviously to the family and those who have terrible experiences in the NHS.”

The PM later dodged questions about the photo of Jack at a media question and answer session, talking instead about his plans to invest in the NHS. It was after this that Mr Hancock was dispatched to Leeds.

Speaking after his visit to the hospital, the health secretary said: “To tell you the truth, I was horrified.