Olympic champion hammer thrower Dilshod Nazarov of Tajikistan has been handed a backdated two-year doping ban, the Athletics Integrity Unit (AIU) said on Thursday. He thus won't be able to defend his title at this year's Tokyo Olympics.

The AIU said in a statement the 38-year-old's samples from the 2011 world championships in Daegu, South Korea, in which he finished 10th in the event, had been re-tested and found to contain a prohibited substance. He has been banned starting from September 24, 2019.

All of his results between August 29, 2011 and August 29, 2013 are now disqualified and Nazarov will not be allowed to compete at the Tokyo Games which are due to begin on July 23.

Nazarov won the men's hammer event at Rio 2016, as the Central Asian country's first gold medal since it gained independence with the 1991 collapse of the Soviet Union.

He won silver in the 2015 world championships and gold medals in the Asian Games in 2006, 2010 and 2014.