Sir Alex Ferguson said he is concerned there may be a "sinister" reason behind the lack of penalties awarded to Manchester United this season.
Ferguson was angry when referee Neale Barry ignored claims for a foul on Alan Smith in Sunday's game with Newcastle.
"It is getting ridiculous now. I am not sure if they are instructed but it is looking sinister to me," said Ferguson.
"That is the same referee who gave Portsmouth a penalty against us for the slightest tug by Rio Ferdinand."
Ferguson said he felt United were paying the penalty for a debatable penalty awarded to them against Arsenal when Sol Campbell was judged to have felled Wayne Rooney.
United went on to win 2-0 in the match which ended Arsenal's record 49-match unbeaten run.
"Since that penalty kick against Arsenal, it seems to me we are not going to get another no matter what the circumstances," he said.
"One of our players will need to get shot for us to get one."
United have been awarded two penalties since the Arsenal match in October 2004.