A British-Pakistani man and three others accused of the 2002 murder of Wall Street Journal reporter Daniel Pearl have been rearrested in Pakistan a day after a court acquitted them.

Ahmed Omar Saeed Sheikh and three alleged accomplices in the kidnapping and killing of the US journalist are to remain in detention for three months pending the filing of an appeal, Pakistan's interior ministry said in a statement on Friday.

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A Pakistani court sparked outrage on Thursday after it overturned Sheikh's death sentence, issued by an anti-terrorism tribunal in 2002, but handed him seven years in prison, on the lesser charge of kidnapping Pearl, a term he has already served.

Three of his co-defendants who were handed life prison terms in 2002 were acquitted.

On Friday, the Sindh provincial government's Home Department issued the order to arrest and detain the four before they were released from prison.

"The government of Sindh has sufficient reason that Ahmed Omar Sheikh and Fahad Nasim Ahmed, Syed Salman Saqib, Sheikh Muhammad Adil be arrested and detained for a period of three months from the date of arrest [April 2, 2020]," a top official of the department said in the order.

The official cited concern that the released men may act "against the interest of the country".

The law to keep them in detention is one that the government has often used to keep high-profile suspects, in custody after being unable to successfully prosecute them in court.

Pearl, 38, as the South Asia bureau chief for The Wall Street Journal, was investigating armed groups in the city of Karachi, the capital of Sindh, after the September 11, 2001, attacks on the US when he was kidnapped in January 2002. He was beheaded weeks later.

'Full measure of justice'

The rearrest of the four men gives the government time to put together a legal appeal against their acquittal.

The appeal will be filed next week in the Supreme Court, the country's top court, by the Sindh provincial government, Pakistan's interior ministry said in a statement on Friday.

"Ministry of Interior, Government of Pakistan reiterates its commitment to follow due process under the laws of the country to bring terrorists to task," the statement added.

The US denounced Thursday's court acquittal of the four, with the top US diplomat for South Asia writing on Twitter that it was "an affront to victims of terrorism everywhere".

"We welcome Pakistan's decision to appeal the verdict," acting US Assistant Secretary of State for South and Central Asian Affairs Alice Wells said.

"Those responsible for Daniel's heinous kidnapping and murder must face the full measure of justice."

The United States will not forget #DanielPearl. We continue to honor his legacy as a courageous journalist and demand justice for his brutal murder. https://t.co/wrN3MdeETP — Secretary Pompeo (@SecPompeo) April 3, 2020

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

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