Several of the 17 prisoners condemned to be put to death in the US by the end of January are likely to receive a temporary reprieve after a commercial drug company said it had run out of the anaesthetic widely used as part of the lethal injection.

The Illinois-based pharmaceutical company Hospira said it had suspended the production of Pentothal because it could no longer obtain a sufficient quantity of the drug's active ingredient from a separate firm.

The firm – the drug's sole producer – said the delay could last until next March.

Pentothal consists of sodium thiopental, a barbiturate used as an anaesthetic in hospital operations. It is also one of the three drugs combined in the lethal cocktail that makes up the most common form of death penalty in the US today.

Some 33 of the 35 states that still put prisoners to death use the three-drug approach. The remaining two, Ohio and Washington, have opted for using a single heavy dose of sodium thiopental.

The shortage has already lead to the postponement of executions in Oklahoma and Kentucky. Arizona announced it had run out of the drug and was unlikely to be able to go ahead with an execution scheduled for late next month.

California, which is seeking to resume lethal injections after a five-year hiatus, is also facing delays.

Richard Dieter, the director of the Death Penalty Information Centre, in Washington, said the supply problem highlighted the contradictions of using a medical process to end life.

"This kind of thing was bound to happen," he said. "There will be more of these sorts of problems so long as you try to use a medical method for executions."

Some proponents of capital punishment in the US have suggested that Hospira may have orchestrated the lack of supply because it opposes the use of its product for death sentences. In a statement, the company insisted the shortage was due to a breakdown in the supply chain.

But it also reiterated its longstanding complaint about the use of its drug in executions, saying: "Hospira manufactures this product because it improves or saves lives, and the company markets it solely for use as indicated on the product labelling.

"The drug is not indicated for capital punishment, and Hospira does not support its use in this procedure."

In the most fraught case, two death row inmates in Oklahoma are awaiting execution but the state only has enough sodium thiopental to kill one of them. That has led to a flurry of activity by lawyers for the two men forcing the courts to intervene to decide which of the two should die.

"This is a form of Russian roulette," Dieter said.

The one state that appears not to have a shortage of the drug is Texas, which executes the most people. The state has three executions scheduled before the end of the year, which would take its total number for 2010 to 15.

If the delay continues into next year, states are likely to have to seek an alternative drug to replace Pentothal – but that could lead to further ethical questions about the use of medical drugs to kill people and provoke lengthy legal challenges.