Kyle Chisholm has been disqualified from last weekend's Salt Lake City round of the AMA Supercross championship, and banned from this weekend's Las Vegas season finale, for blocking title contender Chad Reed in Saturday's main event.

Chisholm, who was being lapped, allowed Yamaha team-mate and title leader James Stewart to pass without problem, but made things difficult for Suzuki rider Reed (pictured) - then made contact with the reigning champion after he finally found a way past.

As a result, Chisholm has been found guilty of violating Appendix A2.3, paragraph "i," of the AMA Supercross an FIM World Championship rulebook, which prohibits "engaging in any unfair practice, misbehaviour, or action detrimental to the sport of motorcycling in general..."

Chisholm also violated Appendix A.2.3 paragraph "o" which prohibits "failing to immediately respect and comply with the operational or warning flags/lights or other signals from Racing officials" when he remained on track after being shown the black flag.

In addition to his disqualification and suspension, Chisholm was also fined $5000.

Stewart will start this weekend's event with a six point lead over Reed.