Scot Muir took five seconds off the 31-year-old mark while competing at the Muller Indoor Grand Prix in Birmingham.

However, a sportswear manufacture is reportedly seeking "clarification" whether her shoes were prototypes.

The IAAF said there is "no evidence" that the shoe breaches rules.

However, it added: "If we do receive a complaint, our process is to refer the shoe for study and if it is proved to be non-compliant, it may be prohibited in competition."

Muir, the European champion over 1500m indoors and outdoors, was wearing spikes that appeared similar to those worn by Eliud Kipchoge when he set a new marathon world record last year.

Manufacturer Nike claims the shoe gives a 4% improvement in "running economy".

If the spikes are prototypes and not widely available to buy, they may breach IAAF rule 143.2, which states "any type of shoe used must be reasonably available to all in the spirit of the universality of athletics".