An Alabama man convicted of murdering a woman during a robbery thirty years ago was executed late Thursday.

Willie Smith, 52, was put to death by lethal injection at 9.47pm Central Time (0247 GMT) at a prison in southwest Alabama.

"Justice has been served. Tonight, Willie Smith was put to death for the heinous crime he committed nearly three decades ago: the abduction and execution-style murder of an innocent young woman, Sharma Johnson," Alabama Attorney General Steve Marshall in a statement.

Smith had been on death row for 30 years after being convicted of the 1991 murder of 22-year-old Sharma Ruth Johnson in Birmingham.

Smith was granted an 11th-hour stay of execution in February after the Supreme Court ruled that barring a priest from being by his side during his death was unlawful.

Prison officials have since said they would allow Smith's pastor to be present but his lawyers had been seeking to halt the execution on other grounds.

They argued that Smith was intellectually disabled and had not been allowed to choose the manner of his execution.

In 2018, Alabama approved the use of nitrogen gas as a means of execution in addition to lethal injection.

Because of his mental disability, Smith - who had an IQ of around 70 - could not understand that he was able to choose this method of execution, his lawyers said.

The Supreme Court rejected a late request for a stay by Smith's lawyers on Thursday and the execution was allowed to proceed.

Capital punishment has been abolished in 23 US states, while three others - California, Oregon and Pennsylvania - have observed a moratorium on its use.