An auxiliary bishop with the Archdiocese of Newark, in America, has been attacked during Mass.

Essex County authorities say the attack occurred on Saturday at Cathedral Basilica of the Sacred Heart during an event honouring baseball Hall of Famer Roberto Clemente.

They say 48-year-old Newark resident Charles Miller was in a pew when allegedly he got up, went to the altar and punched Fr Manuel Cruz in the mouth. Fr Cruz was treated at a hospital for undisclosed injuries that aren't considered serious.

Miller was charged with assault. Authorities declined to comment on a possible motive for the attack.

The Mass marked the recent anniversary Clemente's death on New Year's Eve in 1972. He was killed in a plane crash while trying to bring supplies to the earthquake-ravaged country of Nicaragua.