Washington: The Obama administration bluntly urged the US Congress on Thursday to steer clear of directing where terrorism suspects should be prosecuted, pushing back against efforts to require military rather than civilian trials.

A bipartisan group of senators has offered legislation aimed at forcing the administration to prosecute terrorism suspects, like the self-professed mastermind of the September 11, 2001 attacks, Khalid Shaikh Mohammad, in special military commission trials instead of traditional criminal courts.

US Attorney General Eric Holder ordered Mohammad and four alleged co-conspirators to be tried in a criminal court in Manhattan. But concerns by some lawmakers about security costs and granting full legal rights to the suspects have forced administration officials to reconsider.

Holder and Defence Secretary Robert Gates wrote to leaders in the House of Representatives to express their opposition to legislation directing how and where to prosecute the cases.

Dangerous precedent

"The exercise of prosecutorial discretion has always been and should remain an Executive branch function," they said in the letter to House Speaker Nancy Pelosi and Republican Minority Leader John Boehner.

"We believe it would be unwise and would set a dangerous precedent for Congress to restrict the discretion of our departments to carry out specific terrorism prosecutions," Holder and Gates said.