A head of procurement for the NHS has set up a business to profit from the private sale of huge quantities of personal protective equipment (PPE) in the midst of the coronavirus outbreak, an undercover investigation by the Guardian can reveal.

David Singleton, 42, a senior NHS official in London who has been working at the capital’s Covid-19 Nightingale hospital, launched the business two weeks ago to trade in visors, masks and gowns.

Asked about the findings of the investigation, Singleton said he disclosed his business to superiors in the NHS, in accordance with the rules, and was told there was “unlikely to be a conflict”.

However, the NHS launched an immediate investigation. “We take any potential conflicts of interest extremely seriously and as soon we became aware of these allegations an internal investigation was started,” a spokesperson said.

A website for Singleton’s company, Sure Stock, which marketed PPE to private sector and NHS clients, made no reference to Singleton or his role in the health service. But in a phone call with an undercover reporter posing as a potential client, Singleton confirmed he was running the business. He said he was trading as a “sales agent” between suppliers and buyers of PPE.

According to Singleton’s LinkedIn profile, which he deleted shortly after the Guardian told him about its investigation, he is a head of procurement for the NHS in London. He works within a large commissioning support unit (CSU) that covers the capital’s north and east and surrounding areas. It is understood the investigation is being conducted by his employer, the NHS north and east London CSU.

During the conversation with the undercover reporter, Singleton said he was “currently an NHS employee” but said his role did not involve buying “any products”. “I deliver services,” he said. “So none of the suppliers that I’m working with do I have any interactions with during my day job.”

Asked later whether he was exploiting his NHS expertise and contacts, Singleton said in a statement that he was not “directly involved” in responding to the PPE shortage in the NHS “as my role does not involve purchasing or procuring of these products”.

However, information collated by the Guardian, including internal NHS email evidence, suggests Singleton may have been involved in procuring PPE supplies. Asked to respond to a request for comment about the email evidence, Singleton replied “no comment” and hung up the phone. The NHS declined to comment on the email evidence.

Singleton created his PPE company on 15 April, as the shortage of protective equipment for NHS and other health and care workers working on the frontline of the coronavirus outbreak was reaching crisis point.

His company, Sure Stock Limited, originally registered to Singleton’s home in Essex, launched a website that same week, marketing PPE products for “medical, dental, adult social care, the food industry and personal use”.

The website offered large amounts of PPE and hygiene products for sale, including protective face shields, or “smart visors”, which were priced at £19,500 for minimum orders of 10,000 units.

Posing as an agent for a meat processing factory, a Guardian reporter approached Sure Stock claiming his client urgently needed large quantities of PPE to protect about 800 workers and return the facility to full production.

Sure Stock’s salesperson, a friend and associate of Singleton, confirmed the company had been created by Singleton and said he could help source batches of 20,000 visors, masks, gowns and gloves – as well as 1,000 litres of hand sanitiser – as part of an initial order. The sale would have totalled more than £100,000.

The salesperson told the undercover reporter: “Essentially a friend of mine is head of procurement for NHS London. He has really struggled to get stuff to people in the right timeframe. So essentially what we decided to do was set up a little company and become sales agents for people in the UK who have got stock. And then essentially we would help in linking up the supply chains that are massively disastrous at the moment.”

The undercover reporter then asked to talk to Singleton directly. During a 40-minute telephone conversation, Singleton told the undercover reporter: “What we do is we work with the supplier and then our margin, our commission, our referral, comes from them before the prices go out. So we just work as a sales agent.”

He also disclosed he was an NHS employee. “We want to nurture relationships like yours. Because people like you can open doors for some of my suppliers into areas that they don’t currently reach into,” he told the undercover reporter. “So it’s growing a network of trusted suppliers and buyers because you can’t be a supplier unless you’ve got a buyer. You can’t be a buyer unless you’ve got a supplier. You need to have these things. You need to connect up.”

Towards the end of the call, Singleton emphasised how competitive his visor prices were and encouraged the undercover reporter to “piggyback” a large order “currently … going through with the Far East [and a UK importer]”. He added: “What I’d close off by saying is when you are in a position where you know you want to place an order, rest assured that you are going to be dealing with a UK company.”

Singleton told the undercover reporter that during the Covid-19 outbreak he had been “redeployed” to the Nightingale hospital at the Excel Centre and the Royal London hospital and was “helping them set up their pop-up ITU [intensive treatment unit] wards and their stock rooms”.

In his statement to the Guardian following the undercover investigation, Singleton said he had not set up ITUs or stock rooms and had not been involved in any procurement at the the hospital.

He said he had notified his employer about Sure Stock, as is required, and had been informed by a superior that “there is unlikely to be a conflict”, as it was perceived there would be no crossover in terms of customers. Singleton said declaring the directorship was the main step towards compliance and this had been completed.

However, the Guardian understands that while Singleton recently declared his new business via an internal online NHS reporting system, the disclosure was under review and had not yet been approved.

In his conversation with the undercover reporter, Singleton’s salesperson appeared to give conflicting accounts of whether or not the firm planned to market to the NHS. At one point he said: “We’re not really wanting to approach anyone in the NHS, because there is a bit of conflict of interest, so we are sort of staying out of that.”

But during another part of the conversation, about the scarcity of gowns on the market, the salesperson said: “We’ve got a lot of NHS trusts frantically phoning around trying to get hold of these and they can’t.” He added: “Now what we are doing with those, we are offering the NHS 30 days to pay.”

In his emailed statement, Singleton said Sure Stock “has not and will not sell PPE and related equipment to the NHS, or any NHS organisation”. He added: “Any such allegation is false”.

However, a photograph on Sure Stock’s website advertising face shields showed a visor with the NHS logo printed on the front, and the company offered deals for NHS clients. “For our NHS heroes your price is fixed!” the website stated.

In his statement, Singleton said the face shields have not been sold to the NHS because they did not meet the complex medical devices regulations which govern the manufacture and supply of such products.

Sure Stock’s website was mothballed shortly after Singleton was contacted by the Guardian for comment. It now just states: “Coming soon”.