Washington - A judge rejected an immunity plea by former White House intern Ms Monica Lewinsky yesterday. She could now face prosecution for obstruction of justice in a scandal involving President Clinton, US television networks reported.ABC and CBS both reported the the secret decision, that had yet to be announced publicly.Ms Lewinsky is at the centre of an investigation by independent counsel Mr Kenneth Starr into allegations that she had an affair in 1995 with Mr Clinton and that he urged her to lie about it under oath.Both have rejected the claims.