A major drugs supplier to the NHS could be complicit in the executions of nine US prisoners on death row, a human-rights charity claimed yesterday.

Reprieve revealed that pharmaceutical giant Mylan has ignored warnings that one of its drugs could be used to kill inmates in Alabama.

Investigator Maya Foa told company bosses in September that the firm is the only US-approved supplier not to have put in place controls that stop its drugs from being used in executions.

She warned that there is “a very real risk that Mylan may soon become the go-to provider of execution drugs for states across the country.”

Mylan describes itself as a “leading developer and supplier of generic medicines (to) wholesalers and throughout the National Health Service.”

The southern US state plans to use rocuronium bromide made by Mylan as the second part of a new three-stage lethal cocktail in planned executions. The paralysing agent leaves the prisoner unable to speak or move.

Human rights groups have warned that it can mask the effects of a botched execution but Alabama’s attorney general is seeking to fast-track the executions of nine people.

Yesterday Ms Foa said: “Mylan is the only company we have worked with which has so far failed to take any concrete steps to prevent its medicines from being used to end the lives of prisoners in the US.

“The NHS should think carefully about supporting a company which is apparently happy to see its medicines used in brutal executions.”