Jeremy Hunt's "highly irresponsible" rhetoric about NHS weekend services could have put patients at risk, Labour claimed after researchers suggested the Health Secretary's criticisms had put people off attending at A&E units.

Results of a two-week long national survey suggested that two deaths were reported "as a result of delayed presentation", while more than 80% of the cases covered were deemed to have had a "worse outcome" due to the delay in seeking medical attention.

Officials stressed that anyone with health concerns should seek advice as soon as possible but insisted the Government "makes no apology" for its drive to ensure a seven-days-a-week NHS.

In a letter to the British Medical Journal, Hoong-Wei Gan and Constantinos Kanaris condemned the way Mr Hunt and other ministers had chosen to highlight the so-called "weekend effect".

They wrote: "Unfortunately, misinterpretation and public statements by various members of the government including the Secretary of State for Health, the Rt. Hon. Jeremy Hunt, blaming the 'weekend effect' firstly on a lack of consultants, then junior doctors, has been associated with a significant number of patients delaying their presentations to frontline services such as A&E and out-of-hours GP surgeries, based on the misconstrued belief that there is a lack of doctors over the weekend and they are more likely to die as a result of this."

The two doctors' two-week national study, carried out between October 6 and 20, was aimed at determining the impact of the "Hunt effect" - patients presenting on a weekday despite having had symptoms at the weekend due to concerns that "there are no doctors" on Saturdays or Sundays.

The two surveys - one epidemiological, one clinical - collected information on 40 cases.

Analysis of the clinical database found "two deaths were reported as a result of delayed presentation, whilst 31.7% of cases suffered long-term, irreversible morbidity".

"Overall, 82.4% were deemed to have had a worse outcome as a result of their delayed presentation and 90% were reported as having the potential to be life-threatening," the writers said.

The authors accepted their study could not definitively prove a link between Mr Hunt's public comments and delayed presentation, but they said the association between Mr Hunt's comments in July and October and an "increasing number of patients not presenting to frontline services in a timely manner" was "concerning".

They added: "It is particularly concerning that two deaths were possibly attributed to the delayed presentation, that the vast majority of patients were at risk of significant harm as a result, and that nearly 30% of patients could have avoided hospital admission altogether."

Shadow health secretary Heidi Alexander said: "These worrying findings should make Jeremy Hunt stop and think about the unintended consequences of his rhetoric on the NHS.

"As the study suggests, Jeremy Hunt's actions may have put patients at risk and potentially caused unnecessary harm.

"To imply that the NHS isn't there for you in an emergency is not only completely wrong, but highly irresponsible.

"Jeremy Hunt should now issue clear advice to patients that if they need urgent medical help they should seek it without delay, regardless of the day of the week."

A Department of Health spokesman said: "Anyone with health concerns should seek advice as soon as possible through emergency services such as 999 and 111.

"However, there is clear clinical evidence that standards of care are not uniform across the week and this Government makes no apology for tackling the problem to make sure patients receive good quality care 24 hours a day, seven days a week."