Doctors’ leaders have criticised plans to force all hospital consultants to reveal how much they earn from treating private patients on top of their NHS work.

Consultants reacted angrily to the move, which they claimed was unfair and amounted to “smearing” senior doctors who devoted their lives to the NHS.

The Hospital Consultants and Specialists Association (HCSA) said publication could unfairly tarnish the reputation of the medical profession because most senior doctors did no private work.

“Doctors across the UK work hard, often beyond their contracted hours, to deliver for NHS patients. Yet once again we are seeing a few individual cases being used to misrepresent an entire profession, a large majority of whom do no private work at all,” said Eddie Saville, the union’s chief executive.

Consultants who contacted the HCSA in the wake of the announcement voiced concern that NHS England was “smearing doctors, portraying them as highly paid and overpaid”. There was also suspicion that the move was designed to deflect attention from problems in the NHS.

Saville took a thinly veiled swipe at NHS England, which has decided to compel all hospitals to disclose their consultants’ private earnings through a register that will come into effect from next year. It is making the change after a review of conflicts of interest across the NHS.

“One has to question the motivation for publicising this at a time when there are far bigger issues elsewhere,” said Saville, whose organisation represents about 3,000 of the 40,000 consultants working in the NHS in England. Highlighting consultants’ private income would do nothing to tackle problems such as underfunding of the NHS, growing demand, low morale and understaffing, he added.

He denied that doctors who undertook private work were shortchanging their NHS patients. “NHS hospital doctors already agree with their trusts a job plan including their NHS and private practice, so the idea that this is somehow impacting on NHS patient care doesn’t add up,” he said.

The British Medical Association stressed that consultants only took on private work after first offering to do extra hours for their NHS trust.

“Under the terms of the consultant contract, if a doctor wishes to undertake private work, they have to first offer extra time to the health service on top of any working hours they already perform,” said Dr Keith Brent, the chair of the consultants committee at the doctors’ union.

In addition, he said, consultants, like all other senior NHS staff, were required to make an annual declaration of substantial conflicts of interest in accordance with legislation.

The HCSA and BMA were responding to comments by the NHS England chairman, Prof Sir Malcolm Grant, that in the conflicts of interest review “private medicine came up as an area of concern, particularly in the larger teaching hospitals”.

“It’s not an attempt to curb private work by consultants. Let’s just have some transparency here. Much of what goes on in these communities is almost under the radar,” Grant told the Times.

Specialties such as surgery, anaesthesia, cardiac care, ophthalmology and obstetrics and gynaecology often throw up opportunities for consultants to undertake private work, particularly in cities such as London. But other branches of medicine, including geriatrics and acute medicine, do not.

Data collected by the Royal College of Physicians, which represents hospital doctors in England, shows that in 2015-16 consultants in 30 different medical specialties worked on average 46.4 hours a week for their NHS trust – 4.3 unpaid hours more than the 42.1 hours they were typically contracted to undertake.

NHS Digital’s most recent figures for the annual earnings of the health service’s 1.4m staff in England showed that doctors of all types, apart from GPs and locums, earned an average of £59,588 last year from the NHS, 0.4% more than the year before.

However, while consultants received mean annual basic pay of £83,746, their average mean earnings overall from the NHS were £111,863, once £28,117 of other earnings was taken into account.

More than 10% of doctors earn between £85,000-£91,000, almost 11% are paid £97,000-£103,000, and more than 6% earn £91,000-£97,000, according to the figures.

Small numbers of doctors earn more than £103,000-£109,000.

Labour’s Diane Abbott, the shadow health secretary, welcomed the “long overdue” transparency over consultants’ income from both private practice and also in payments from drug companies.

But she added: “This new transparency should be extended. The government should publish in full how much the private sector is siphoning from the NHS, including via their own new sustainability and transformation plans.”