Churchill Downs, home of the famed Kentucky Derby, will suspend racing at the conclusion of this weekend's competition to examine safety measures after 12 horse deaths in the past month, officials said on Friday.

With operations shut down at the iconic track in Louisville, Kentucky, the remainder of its Spring Meet, scheduled to run to July 3, will be relocated to Ellis Park in Henderson, Kentucky, starting on Saturday, June 10.

Churchill Downs Incorporated said in a statement on Friday that officials would conduct a "top-to-bottom review of all safety and surface protocols and integrity measures in collaboration and consultation with nationwide experts."

The move comes a day after Churchill Downs announced that new safety measures would be implemented aimed at improving horse safety.

Those moves included restricting horses to four starts in a rolling eight-week span and eligibility bans for horses that do not perform well.

Officials also paused a programme of track-based incentives, including trainer start bonuses and purse payout allocations to every race finisher through last place.

But with the reason for the spike in equine fatalities still a mystery, Churchill Downs officials have opted to pursue further evaluation of track safety measures out of "an abundance of caution."

"Following a thorough internal review and concurrent investigations conducted by the Kentucky Horse Racing Commission and Horseracing Integrity and Safety Authority, no single factor has been identified as a potential cause and no discernable pattern has been detected to link the fatalities," Churchill Downs said in a statement.

Mage won the Kentucky Derby on May 6, capping a disturbing week at Churchill Downs where seven horses died within 10 days – two of them euthanised after they were injured in support races on Derby day.

The 11th and 12th fatalities occurred last Friday and Saturday, when Lost in Limbo and Kimberley Dream suffered injuries while racing and were euthanised. (AFP)