In a statement from its solicitors, eHarley Street said it "does not hold any contracts for General Medical Services (GMS) in Wales", but that three partners hold "several contracts" for surgeries that "may have been the subject of the complaints outlined".
It said: "The operation of general practice - is currently under significant financial strain," and that "the surgeries operated by the partners have faced similar challenges".
"While some locum payments have regrettably been delayed, the vast majority have been settled, and the partners are confident that no outstanding payments will remain unpaid."
It said Aneurin Bevan University Health Board had "conducted urgent assurance meetings and practice visits" and found the surgeries were "operating within the parameters of the GMS contract, with no concerns identified regarding patient safety, health and safety, staffing levels, or resources".
"The partners strongly believe that many of the allegations originate from two disgruntled employees, without objective basis or corroboration."
A health board spokesperson said it “does not hold any GMS contracts with e-Harley Street Primary Care Solutions” and that all such contracts were with “named individual GPs”.
The board said: "We are aware of concerns related to a GP partnership within the health board region and are meeting regularly with the GP partners to ensure they are operating in line with their contractual obligations".
"We acknowledge the high demand for primary care services across the country, and this is also experienced here... we are committed to working with and supporting our GP partnerships to provide sustainable and reliable services for our population."