WASHINGTON (Reuters) - Attorney General Eric Holder said on Friday that President Barack Obama acted within his legal authority when Obama unveiled a set of executive actions to try to reduce gun violence.

The chief U.S. law enforcement official and an Obama appointee, Holder spoke two days after Obama ordered more scientific research into gun violence and other changes.

Some Republicans said Obama was improperly bypassing Congress, and at least one said Obama risked impeachment.

"Not one of the executive orders - contrary to what a few have said - impinges upon anyone's Second Amendment rights or is inconsistent with the historical use of executive power," Holder told a committee of the U.S. Conference of Mayors at a Washington hotel.

The Second Amendment to the U.S. Constitution as interpreted by the U.S. Supreme Court guarantees Americans the right to own firearms, with some exceptions.

(Reporting by David Ingram; Editing by Jackie Frank)