Bieber 'asked to undergo paternity test'

Justin Bieber has been asked to undergo a DNA test to determine if he is the father of a fan's baby.

Mariah Yeater claims her son Tristyn Anthony Markhouse Yeater, who was born on July 6, was conceived when she had "unprotected sex" with the pop megastar on October 25, 2010, following a performance at Los Angeles' Staples Center.