A prominent conservative U.S. appeals court judge resigned from the largest association of federal judges over its decision to speak out against a rise in criticism, threats and violence directed at the judiciary in a statement issued after several judges came under attack for blocking Trump administration initiatives.

Key members of the U.S. federal judiciary warned on Tuesday of a rising number of threats directed at their colleagues and described calls to impeach judges over their rulings "concerning" as some Republican lawmakers push to remove jurists who have blocked U.

Top U.S. federal judges have raised alarms over increasing threats and calls for impeachment against their colleagues. U.S. Circuit Judge Richard Sullivan, chair of the Judicial Conferences security committee,