France has asked the US state of Texas to grant a stay of execution to a convicted murderer due to be killed Wednesday and to reexamine the man's claims that he is innocent, officials said.

"Our ambassador in Washington has contacted the governor of Texas to request a reprieve for Mr. Skinner and that his request for an additional enquiry be accepted," said foreign ministry spokesman Bernard Valero.

Both France's President Nicolas Sarkozy and Foreign Minister Bernard Kouchner have expressed their support for Henry "Hank" Skinner to his French wife, Sandrine Ageorges-Skinner, he told reporters.

Skinner, 47, will be executed later Wednesday unless the US Supreme Court and Texas Governor Rick Perry accept his last-minute appeal for DNA testing that he says will show his innocence.

Skinner has pleaded unsuccessfully in the past for authorities to redo DNA tests which he says will show he did not commit the New Year's Eve 1993 murder of his girlfriend and her two sons in his home.

He was sentenced to death by lethal injection after a jury trial in 1995, but contends that additional DNA testing on items that were not examined during his trial would show his innocence.

Texas has executed more people than any other US state. France opposes the use of the death penalty in any circumstances.