The editor of the British Medical Journal (BMJ) has accused Jeremy Hunt of misrepresenting key findings about death rates among patients admitted to hospital at the weekend.

In a letter to the health secretary, Fiona Godlee took issue with him repeatedly claiming that there are 11,000 “excess” deaths among such patients within 30 days of their admission, and blaming that on understaffing at weekends.

Hunt has cited as his source a study co-written by NHS England medical director Professor Sir Bruce Keogh that was published in the BMJ last month, referring to it in parliament and media statements recently to justify the new contract he has threatened to impose on junior doctors in England and the drive to create a seven-day NHS.

However, while the study found that 11,000 more patients a year die after being admitted on a Friday, Saturday, Sunday or Monday than on any other day of the week, it warned that it would be “rash and misleading” to conclude that an exact number of them could have been avoided.

In her letter, Godlee wrote that Hunt’s continued use of the figure of 11,000 deaths despite this important caveat “clearly implies that you believe these excess deaths are avoidable”. She has asked him to clarify the statements he has made about the research “to show your understanding of the issues involved”.

Two doctors last week complained to the Cabinet Office about Hunt’s use of the 11,000 figure and said he has misled MPs.

Ben Gummer, the health minister, defended Hunt’s right to link understaffing in hospitals at the weekend with an increased risk of patients dying.

“Significant independent clinical evidence shows increased mortality in our hospitals at weekends linked to reduced clinical cover. The BMJ authors themselves acknowledge that, and any debate about precisely how many of the thousands of deaths are avoidable misses the point,” Gummer said.

“What all doctors want is to provide the best care for their patients, and the public rightly expect the highest standards whichever day of the week they are admitted to hospital. The government is committed to supporting that.”