Any claims of executive privilege would also be "significantly limited", as part of an agreement between the previous administration and lawyers for Barack Obama, Bush's successor.

The Bush administration had previously claimed that aides were shielded from testifying by executive privilege, sparking a lawsuit from the judiciary committee.

Last July a US district judge rejected Bush's contention that the advisers were immune from the committee's subpoenas and said congress had the power to investigate the executive branch, although the Bush administration had appealed the decision and wrangling over the aides' testimony had continued.

Obama 'pleased'

Greg Craig, Obama's White House counsel, said the president was "pleased" the issue had been resolved.

"The agreement will allow the committee to complete its investigation into the US attorneys matter ... in the way such disputes have historically been resolved - through negotiation and accommodation between the legislative and executive branches," he said.

The controversy over the firings led to the resignation of Alberto Gonzales, the then US attorney-general, in 2007.

Gonzales denied abuse of power but acknowledged the matter had been mishandled.