Human rights group Reprieve said Thursday that groups including the American Nurses Association (ANA) had backed a nurse who refused to force-feed a hunger-striking Guantanamo detainee.

The military nurse refused to carry out the practice - which is banned by the World Medical Association.

In a letter to US Defence Secretary Chuck Hagel last month, the ANA argued that he should not be punished for his decision.

The nurse had his deployment cut short and the US military is considering whether to discharge him or allow him to serve out his remaining years.

If he is discharged, the nurse, who has already served 18 years in the military, would not receive his pension.

Guantanamo Bay still holds 148 men without trial.

"In refusing to force-feed, this nurse did nothing other than stand by his professional ethics," said Reprieve strategic director Cori Crider.

"The Department of Defence must not persecute him for doing the right thing."