WASHINGTON - US?Vice-President Joe Biden was sworn in for a second term in office on Sunday.

Biden took the oath of office from Supreme Court Justice Sonia Sotamayor during a private ceremony at the Naval Observatory, the vice-presidential residence. The ceremony was attended by family and friends.

President Barack Obama will also be officially sworn in at a low-key ceremony later Sunday morning, as required by the constitution. Both Obama and Biden will be sworn in again at a public ceremony at the Capitol on Monday.