Jockey Nathan Berry has been placed in an induced coma in a Singapore hospital, an Australian Jockeys' Association (AJA) statement said on Tuesday.

Berry has been in hospital since he collapsed at trackwork at Kranji racecourse last week.

A statement from Berry's family issued through the AJA said: "Nathan has been diagnosed with Norse Syndrome and has now been placed into an induced coma.

"Doctors do not expect much change over the next few days as they run further tests."

A Sydney jockey, 23-year-old Berry has been riding on a short-term contract in Singapore since the start of the month.

He won the Magic Millions Classic on Golden Slipper-bound colt Unencumbered in January.

His twin-brother, top Sydney jockey Tommy Berry, and father-in-law Glyn Schofield, flew to his bedside last week.