The Pakistan Supreme Court has adjourned the hearing of an appeal by the family of slain American journalist Daniel Pearl against the acquittal of the key accused in the 2002 murder, for four weeks.

Thursday's adjournment came due to the absence of government lawyer Farooq Naek, who was unwell, and following the request of the defence lawyer of key accused, Omar Sheikh, Dawn news reported.

Faisal Siddiqi, who is representing Pearl's family, said he was surprised by the four-week adjournment, saying he had asked for an expeditious handling of the case.

Sheikh and three other accomplices were sentenced to life in prison for their involvement in the journalist's brutal murder.

But the Sindh High Court in April acquitted him, a move that has been highly criticised by the US government, Pearl's family and journalism advocacy groups.

The acquittal is now being appealed separately by the government and Pearl's family, a process that under law could take years.

The Pakistan government has opposed Sheikh's release, saying it would endanger the public.

He is to remain in custody until the appeals are resolved.

Pearl, 38, was the South Asia bureau chief for Wall Street Journal when he was abducted in Karachi in January 2002, Dawn news reported.

A graphic video clip showing his decapitation was delivered to the US consulate nearly a month after his abduction.

Sheikh was arrested in 2002 and sentenced to death by the trial court..