Government to announce export control on overseas sales of propofol after Missouri said it could be used in lethal injections

A bar on exports from the UK of a drug approved for use to execute prisoners in America is to be announced on on Wednesday - a move which could put pressure on the US's already strained death row prisons.

The business secretary, Vince Cable, will publish details of a export control on overseas sales of the drug propofol, which is more usually used as an anaesthetic in hospitals.

The move is being made after Missouri became the first US state to allow propofol to be used in lethal injections, with other states expected to follow suit as they struggle to make up for a shortfall in a key ingredient of the traditional cocktail of chemicals.

"This country opposes the death penalty," said a statement from Cable. "We are clear that the state should never be complicit in judiciary executions through the use of British drugs in lethal injections."

The government's move follows a long campaign by the Lib Dem MP Alistair Carmichael, now deputy chief whip, who led anger about the use of a British-made drug called sodium thiopental in executions in the US, where it has been one of the three key ingredients in lethal injections for three decades.

The coalition announced its first export control on sodium thiopental in November 2010, followed by controls on three further drugs used in lethal injections last year – decisions which prompted other European states to advise their pharmaceutical companies to avoid exports for lethal injection, and later an EU-wide ban.

Following those bans, and controls imposed by manufacturers in the US, some US states have struggled to access supplies of the drugs and there have been reports of delays to planned executions. The total number of executions – all by lethal injection – has dropped slightly in the last few years.

UK anti-death penalty campaigners said they hoped the latest control order would continue to cause difficulties for US states which still use capital punishment, and for other countries that follow US protocols such as Vietnam, and potentially lead to public pressure to abandon the death penalty in "swing" US states such as California.

Another headache for prison and state authorities is a legal challenge by a group of prisoners on death row in Missouri against the choice of propofol for executions, claiming it has no pain-killing properties and so is likely to cause suffering.

"Some states will now be looking to change protocol for a second time; the different method [not lethal injection] is unlikely; swing states will surely consider the viability of executing … [it] doesn't make financial sense," said Maya Foa, a campaigner with London-based anti-death penalty lobby group Reprieve.

UK manufacturers of propofol had said the control order would not affect supply to the medical trade, according to the Department for Business, Innovation and Skills.