WASHINGTON  The Obama administration is preparing to increase the use of military commissions to prosecute Guantánamo detainees, an acknowledgment that the prison in Cuba remains open for business after Congress imposed steep new impediments to closing the facility.

Defense Secretary Robert M. Gates is expected to soon lift an order blocking the initiation of new cases against detainees, which he imposed on the day of President Obama’s inauguration. That would clear the way for tribunal officials, for the first time under the Obama administration, to initiate new charges against detainees.

Charges would probably then come within weeks against one or more detainees who have already been designated by the Justice Department for prosecution before a military commission, including Abd al-Rahim al-Nashiri, a Saudi accused of planning the 2000 bombing of the American destroyer Cole in Yemen; Ahmed al-Darbi, a Saudi accused of plotting, in an operation that never came to fruition, to attack oil tankers in the Straits of Hormuz; and Obaydullah, an Afghan accused of concealing bombs.

Preparations for the tribunal trials  including the circulation of new draft regulations for conducting them  were described by several administration officials familiar with the discussions. A spokeswoman for the military commissions system declined to comment.