WASHINGTON  The Justice Department made public on Friday a plan to expand the tools the Federal Bureau of Investigation can use to investigate suspicions of terrorism inside the United States, even without any direct evidence of wrongdoing.

Justice Department officials said the plan, which is likely to be completed by the end of the month despite criticism from civil rights advocates, is intended to allow F.B.I. agents to be more aggressive and pre-emptive in assessing possible threats to national security.

It would allow an agent, for instance, to pursue an anonymous tip about terrorism by conducting an undercover interview or watching someone in a public place. Such steps are now prohibited unless there is more specific evidence of wrongdoing.

The plan is the latest in a series of steps by the Bush administration to extend key aspects of its counterterrorism strategy beyond the end of President Bush’s tenure. An executive order from Mr. Bush in August rewrote the rules for the nation’s 16 spy agencies, and an administration legislative proposal before Congress would reaffirm that the country “remains engaged in an armed conflict with Al Qaeda.”