The US said it was "deeply concerned" Friday after Pakistan freed one of the suspected masterminds of the 2008 Mumbai attacks despite months of pressure from Washington over militancy.

The statement came as firebrand cleric Hafiz Saeed, who heads the UN-listed terrorist group Jamaat-ud-Dawa (JuD) and has a $10 million US bounty on his head, led prayers and met with supporters in Lahore Friday after his midnight release.

JuD, which has operated freely across Pakistan and is popular for its charity work, is considered by the US and India to be a front for Lashkar-e-Taiba (LeT), the militant group blamed for the attack on India's financial capital.

"LeT is a designated Foreign Terrorist Organization responsible for the death of hundreds of innocent civilians in terrorist attacks, including a number of American citizens," US State Department spokesman Heather Nauert said.

"The Pakistani government should make sure that he is arrested and charged for his crimes."

The $10 million bounty for Saeed first offered in 2012 still stands, Nauert added.

The court's decision to release Saeed after Islamabad failed to provide evidence against him came after US President Donald Trump in August angrily accused Pakistan of harbouring "agents of chaos" and called for a militant crackdown.

The horror of the Mumbai carnage played out on live television around the world as commandos battled the heavily armed gunmen, who arrived by sea on the evening of November 26, 2008.

It took the authorities three days to regain full control of the city, and the attacks, which killed more than 160 people, nearly brought nuclear-armed arch-enemies India and Pakistan to the brink of war.

Saeed, already designated a global terrorist by the US at the time, was later listed as one by the UN also over his alleged role in the attacks.

India expressed its fury at his freedom Thursday, with foreign ministry spokesman Raveesh Kumar accusing Pakistan of attempting to "mainstream proscribed terrorists".

Saeed said he was fighting for independence for Pakistan and Kashmir, according to his spokesman Nadeem Awan.

"I was house arrested for talking about the rights of Kashmiris," Awan quoted the cleric as saying.

A JuD spokesman said Saeed "has no links with terrorism" and said the US comments amounted to interference in Pakistan's internal affairs.

New Delhi has long seethed at Pakistan's failure either to hand over or prosecute those accused of planning the attacks, while Islamabad has alleged that India failed to give it crucial evidence.

It is the third time that the cleric has been released by courts after Islamabad briefly detained him twice in the aftermath of the attacks in November 2008.

Saeed for decades has publicly espoused ending India's rule of the disputed Himalayan Kashmir region, with India accusing him of sending armed militants to the valley.

India and Pakistan, who rule parts of the disputed region, have fought two of their three wars over the territory, with scores of militant groups, including LeT, engaged in a decades-old armed insurgency against the Indian rule.

Addressing his supporters, Saeed blamed India for terrorist activity in Pakistan and said he was fighting for independence for Pakistan and Kashmir, according to his spokesman Nadeem Awan.

Source: AFP