The Government is to investigate “extremely serious allegations” that senior health officials who help decide which drugs are bought by the NHS have been paid to work as consultants for pharmaceutical companies.

Following an undercover investigation, The Daily Telegraph reported that some staff charge as much as £15,000 to arrange “advisory board” meetings for private firms.

The allegations raised concerns that health service officials may have had a conflict of interest when deciding how to spend multi-million budgets for drugs.

A Department of Health spokesman said: “If these allegations are true, this is completely outrageous and amounts to an abuse of the trust that patients place in NHS staff.

“The NHS fraud protection body has launched an urgent investigation and we expect each Trust and Clinical Commissioning Group involved to launch a full inquiry.”

And a spokesman for NHS England said: “These are extremely serious allegations so we have immediately directed NHS Protect to launch a full investigation of each and every case identified by this press report.”

The Telegraph said two reporters had posed as drug company reps trying to sell an epilepsy drug and an adrenalin pen.

A pharmacist at one NHS trust, who has since resigned, said he had a “network” of more than 100 health service officials, known as “payers”, who make decisions about what drugs to buy.

“I’m talking about the payers who will make a decision on which drug they have on the formulary,” he told the undercover reporters.

He said it would cost £15,000 for him to organise an advisory board meeting which would “give you a competitive edge”.

The trust he worked for said he had “correctly declared his independent business with us” but added “we do not have knowledge of work that he undertakes in his own personal time”.

The pharmacist told The Telegraph that he had “never allowed my NHS work to be influenced by my other activities”. He added it was important for the NHS to deal with private firms.

Another NHS staff member said he had recently been at a meeting in Germany in which a drug company took 12 payers to “one of the top 10 hotels in the world”. He claimed that the delegates were paid £500 a day while they were there and all had decided to buy the drug sold by the company concerned.