Pakistan has quietly amended its anti-terror laws to ban those listed as terrorists by the United Nations, a move which paves the way for Islamabad to proceed against suspected masterminds of the 2008 Mumbai attacks.
The change was made by President Mamnoon Hussain on Friday, and published by the law ministry late Monday.
"The amendment means that all individuals and entities listed by the United Nations also stand banned under Pakistani laws now," a senior government official told AFP.
He declined to say what actions were being taken after the change, and analysts said it was unclear why it was needed when Pakistan is already a member of the UN.
The move comes after Washington piled pressure on Pakistan last November to take action against Hafiz Saeed, the alleged mastermind of the Mumbai attacks which killed 166 people, after he was released from house arrest in the eastern city of Lahore.
Pakistan says there is not enough evidence to charge him, and denies harbouring militants.
However, the White House has said that freeing him "belies Pakistani claims that it will not provide sanctuary for terrorists".
Security analyst Amir Rana said the Pakistani move may have been in anticipation of the meeting in Paris next week of the Financial Action Task Force (FATF), an inter-governmental organisation to combat money laundering and terrorist financing.
Observers say Pakistan fears being put on money laundering and terrorist financing lists.
Saeed heads the charity Jamaat-ud-Dawa (JuD), believed to be a front for Lashkar-e-Taiba (LeT), a militant group that battles Indian troops in disputed Kashmir and was blamed for the Mumbai attacks.
Six Americans were among those killed during the three-day siege in Mumbai, when gunmen who arrived by sea sparked battles with Indian commandos.
The drama brought nuclear-armed India and Pakistan to the brink of war.
Saeed, who has a $10 million US bounty on his head, has denied involvement. He was listed by the UN in December 2008 for being associated with LeT, as well as having links to the Al-Qaeda terror network and Taliban militants.
JuD is similarly listed by the UN as a terrorist group. No officials from the charity were immediately available for comment.