Christopher Morales Williams’ 400m indoor world record cannot be ratified because of “an issue with the starting blocks”.

The 19-year-old Canadian ran 44.49 seconds at the SEC Indoor Championships in Arkansas on Saturday.

Reports, external said the blocks did not comply with World Athletics regulations.

The US Track & Field and Cross Country Coaches Association said, external Morales Williams’ time will remain “an all-time world best”.

American Kerron Clement set the indoor indoor world record of 44.57 at the same track in Fayetteville in 2005.