Four men acquitted in the kidnapping and killing of American journalist Daniel Pearl in Pakistan have been rearrested and will stay in jail while prosecutors appeal the ruling, officials said.

A Pakistani court sparked outrage in the US on Thursday after it overturned the death sentence of British-born militant Ahmed Omar Saeed Sheikh as well as the convictions of three alleged accomplices in the 2002 murder. 

Pakistan's interior ministry said late yesterday the four would remain in jail while prosecutors appeal their acquittals in the country's Supreme Court. 

The men have been rearrested and will be detained "for a period of three months pending filing of the appeal", the interior ministry said. 

The statement reiterated the government's "commitment to follow due process under the laws of the country to bring terrorists to task". 

Daniel Pearl, 38, was the South Asia bureau chief for The Wall Street Journal when he was abducted in Karachi in January 2002 while researching a story about Islamist militants.

A graphic video showing his decapitation was delivered to the US consulate in the city nearly a month later. 

Alice Wells, the top US diplomat for South Asia, called the overturning of the sentences "an affront to victims of terrorism everywhere".

She welcomed yesterday's decision to appeal.

"Those responsible for Daniel's heinous kidnapping and murder must face the full measure of justice," Ms Wells wrote on Twitter.

US Secretary of State Mike Pompeo tweeted that the US would not forget Mr Pearl.

"We continue to honor his legacy as a courageous journalist and demand justice for his brutal murder," Mr Pompeo said.

Mr Pearl's killing provoked international revulsion at the time, putting pressure on Pakistan's then military government just as it was trying to remake its image following years of backing for the hardline Islamist Taliban in neighbouring Afghanistan.