The U.S. and Qatari governments have agreed to block Iran from accessing any of the $6 billion it gained access to as part of a prisoner swap deal between the Biden administration and Tehran last month, Deputy Treasury Secretary Wally Adeyemo told House Democrats on Thursday, according to three sources familiar with his remarks, two of whom were in the room.

Punchbowl News was first to report on Adeyemo’s comments.

The decision comes as the administration faced bipartisan pressure to block Iran’s access to the money as U.S. officials continue to investigate whether Iran had any direct involvement in Hamas’ terrorist attack on Israel. The Biden administration has said the $6 billion in unfrozen Iranian oil assets could be used by Tehran only for humanitarian assistance.

The money was transferred last month from a South Korean bank to a bank in Qatar. Iran could only access the money through a series of steps, including oversight by the Treasury Department, administration officials have said.