Arizona has devised a new way of sidestepping an EU ban on the supply of lethal injection drugs to US jails - inviting lawyers to procure them on their clients' behalf.

The new protocol is the latest attempt by authorities to tackle the problem of carrying out executions without two key drugs pentobarbital, a sedative and sodium thiopental, an anaesthetic.

States where the death penalty is still in force have had to adopt an array of measures to carry out executions without the drugs which were a key part of a cocktail used in lethal injections.

They have been forced to seek alternatives since 2011 when Lundbeck, the Danish manufacturer of pentobarbital banned its use for executions. The European Commission outlawed the sale of sodium piothental for the same purpose in March 2012.