A further 45 athletes have tested positive for banned substances after a second set of samples were re-analysed from the London and Beijing Olympics.

Of these, 23 were medallists from the 2008 Games, according to the International Olympic Committee (IOC).

IOC president Thomas Bach added that his organisation was committed to the "fight against doping".

All athletes found to have infringed anti-doping rules will be banned from competing at the Rio Olympics.

Those Games begin on 5 August.

The latest results bring the total number of athletes who have tested positive from 2008 and 2012 to 98.

Two more sets of retesting are due to take place as the crackdown continues.

Key details from second wave of retesting:

-386 samples selected from 2008

-30 athletes tested positive

-From four sports and eight countries

-138 samples selected from 2012

-15 athletes tested positive

-From two sports and nine countries

First wave of retesting:

-454 samples selected from 2008

-30 athletes tested positive

-From six sports and 12 countries

-265 samples selected from 2012

-23 athletes tested positive

-From five sports and six countries

The athletes, relevant national Olympic committees and international federations are in the process of being informed about the latest test results.