Saudi and international rights groups have asked Saudi Arabia's authorities to prevent the execution of a man who has been tried twice for the same crime committed 27 years ago.

Abdullah Fandi al-Shammari faces execution next Tuesday over a killing committed in 1981, the unofficial Saudi group Human Rights First Society said in a statement on Wednesday. The victim died a day after a fight with Shammari in a dispute over camel herds.

Shammari was found guilty of manslaughter in 1988 and ordered to pay blood money for accidental death, but was then sentenced to death in 1992 after the case was reopened by the victim's family, Amnesty International said last week.

After intervention from Crown Prince Sultan bin Abdul-Aziz he was given a brief reprieve on November 15 to allow his family to seek a pardon from the victim's family, according to Saudi custom, Amnesty said.

"His case was heard and determined in one session; he has no access to the file or to any legal assistance, and was not able to appeal against the sentence before it was ratified by the court of cassation," Amnesty said.

A spokesman for the government's official Human Rights Commission was not available for comment.

Executions are usually carried out by public beheading in Saudi Arabia, which says it is applying Islamic law. Rights groups say judges often deny defendants the right to a fair trial.