More than a third of GPs on clinical commissioning group (CCG) boards have a financial conflict of interest due to directorships or shares in private companies.
Using Freedom of Information (FOI) requests, the British Medical Journal (BMJ) found 36% of 1,179 GPs in executive positions had a financial interest in a health service provider from which they could potentially commission services.
Moreover the majority of GPs on some CCG Boards had financial interests in the same private healthcare provider.
The BMJ found that 23% of 2,426 governing body members – including clinical, lay and managerial representatives – have financial stake in a for-profit company.
According to the BMJ, this is the "clearest evidence to date" of the conflicts GPs will have to manage from April 1.
Last week the British Medical Association (BMA) UK Consultants' Committee expressed concern about the "clear conflicts of interest for GP commissioners who run private companies".
All CCGs found to have notable conflicts told the BMJ they had "robust systems" in place to manage potential conflicts.
Michael Dixon, chair of NHS Alliance said; "Placing too much emphasis on the issue may prevent clinical commissioners from brining more care into community settings."
The NHS Commissioning Board said it would shortly be publishing "final, comprehensive guidance on managing conflict of interest".
A DH spokesperson has pledged to strengthen Monitor's power to act where "conflicts may affect the integrity of a commissioner's decision".