London 1500 metres silver medallist Gamze Bulut is under investigation by the IAAF for a possible doping violation.

The Turkish Athletics Federation says the IAAF has asked Bulut to submit a defence over irregularities in her biological passport.

Local television reports the IAAF found abnormalities in blood samples from 2011, 2012 and 2013, with the runner suspended pending the investigation.

Bulut is the fifth runner from the 2012 Olympic final to face drug allegations.