The United States on Friday said it was "deeply concerned" over Pakistan's release of Hafiz Saeed, an Islamist leader accused of masterminding the deadly 2008 attacks in Mumbai.
Saeed, who Washington says is a leader of Lashkar-e-Tayyiba (LeT) -- designated in the US as a terrorist group -- was put under house arrest in January following increased pressure on Islamabad to rein in militant groups.
On Wednesday however a Pakistani court released Saeed after Islamabad failed to back the charges of terrorism with evidence.
"The United States is deeply concerned that ... Saeed has been released from house arrest in Pakistan," State Department spokeswoman Heather Nauert said.
"The Pakistani government should make sure that he is arrested and charged for his crimes."
LeT is accused of several bloody attacks, most notably the 2008 Mumbai attack that left nearly 166 people dead, including six US citizens and other Western nationals.
Nauert said that LeT is "responsible for the death of hundreds of innocent civilians in terrorist attacks, including a number of American citizens."
Saeed was declared a global terrorist by the United States and the United Nations over his alleged role in the Mumbai attacks.
"Since 2012, the United States has offered a US $10 million reward for information that brings Saeed to justice," Nauert said in a statement.
On Wednesday Indian officials expressed their outrage over Saeed's release.
"India, as indeed the entire international community, is outraged that a self-confessed and a UN proscribed terrorist is allowed to walk free and continue with his evil agenda," said Raveesh Kumar, India's foreign ministry spokesman.
"It also appears to be an attempt by the Pakistani system to mainstream proscribed terrorists," Kumar said.
Saeed heads the charity group Jamaat-ud-Dawa (JuD), which has operated freely across Pakistan and is popular for its charity work but is considered by the United States and India to be a front LeT.
US President Donald Trump in August angrily accused Islamabad of harboring "agents of chaos" while Secretary of State Rex Tillerson has said too many extremists are finding sanctuary in Pakistan.