Arizona paid $27,000 for a shipment of sodium thiopental, but the FDA seized the drug from a British Airways flight.
A shipment of an illegally imported lethal injection drug bought by the state of Arizona has been stopped at Phoenix airport, according to documents.
Arizona paid nearly $27,000 for the batch of anaesthetic sodium thiopental, which has been used to carry out executions but is no longer manufactured by companies approved by Food and Drug Administration (FDA).
When the drugs arrived on a British Airways flight at Phoenix International Airport, they were seized by federal officials and have not been released, Associated Press news agency reported.
Andrew Wilder, a spokesman for the state Department of Corrections, said: "The department is contesting FDA's legal authority to continue to withhold the state's execution chemicals."
The documents obtained by AP are part of a lawsuit against the department over the transparency of its executions.
Arizona, along with other states with the death penalty, have struggled to obtain legal execution drugs for years after European companies refused to sell those needed to carry out death sentences.
States have had to change the combinations of drugs used in lethal injections or put executions on hold.
Earlier this year, Nebraska was told by the FDA that it could not legally import sodium thiopental after the governor said the state had obtained the drug from India.
Ohio, which earlier this month halted executions until at least 2017 because of a lack of drugs, sent a letter to the FDA stating it believed it could obtain the drug overseas without violating any laws.
On Thursday, Texas said it had obtained a licence from the US Drug Enforcement Agency (DEA) to import sodium thiopental.
Jason Clark, a spokesman for the Texas Department of Criminal Justice, was unable to say whether the state had purchased or received any drugs from overseas.
Last year, Governor Jan Brewer ordered an investigation into the Arizona's execution process after Joseph Rudolph Wood, 55, took nearly 2 hours to die in a Florence prison.
Wood had been injected with 15 times the intended dosage of a sedative and painkiller.
Source: Sky News, October 23, 2015
