Pakistan's government on Friday appealed to the Supreme Court to review its decision to free a British-born Islamist and three others convicted of beheading US journalist Daniel Pearl in 2002.
The United States has expressed concern over the ruling and top US diplomat Antony Blinken repeated a call for accountability in his first phone call with Pakistan's foreign minister on Friday.
A panel of three judges of the court on Thursday acquitted Ahmad Omar Saeed Sheikh and three other Islamists, who had been convicted in 2002 on charges of kidnapping and murder of the Wall Street Journal reporter.
The court ordered the men to be released forthwith if not required in any other case.
The government in Sindh province filed a petition asking the top court to review its decision, the Pearl family's lawyer, Faisal Siddiqi, and a government prosecutor told Reuters.
"We have filed three review petitions," prosecutor Faiz Shah said, explaining that the petitions would seek a reversal of the acquittal and the reinstatement of Sheikh's death penalty.
"Being aggrieved of and dissatisfied with the judgment, the petitioner files an instant criminal review petition for leave to appeal on matters of law, facts and grounds," the petition said.
The release orders would stand irrespective of the review petition, provincial law minister Murtaza Wahab told Reuters.
"We haven't received the release orders yet," he said, adding that the Islamists were not likely to be freed over the weekend, as it usually takes some days for court orders to be sent to prison authorities.
Pearl, 38, was investigating Islamist militants in Karachi after the Sept. 11, 2001, attacks on the United States when he was kidnapped. A video of his beheading emerged weeks later.
His parents expressed shock over the Supreme Court's decision
Secretary of State Antony Blinken on Friday "reinforced" US concern over the case in a call with Shah Mahmood Qureshi, Pakistan's minister of foreign affairs, according to the State Department.
The two "discussed how to ensure accountability" for Sheikh and others responsible for Pearl's kidnapping and murder, according to a readout of a call.
On Thursday, Blinken called the ruling "an affront to terrorism victims everywhere, including in Pakistan" and said Washington was prepared to prosecute Sheikh in the United States.