WASHINGTON - Raging against a political firestorm, US President Donald Trump on Friday shot a sharp warning at his ousted FBI director about possible "tapes" of their disputed private conversations, raising the provocative possibility that recording devices have been installed in the White House.

Trump's top spokesman refused to comment on whether listening devices are active in the Oval Office or elsewhere, a non-denial that recalled the secretly taped conversations and telephone calls that ultimately led to president Richard Nixon's downfall in the Watergate scandal. Trump's warning to fired FBI chief James Comey prompted new accusations of interference in an investigation into allegations of collaboration between Russia and the Trump presidential campaign last year.

It also escalated a potentially damaging standoff between a president and the unorthodox lawman he dismissed three days earlier. Not to mention Congress, which is also investigating.