Olympic champion Ohuruogu hangs up spikes

British athletics great Christine Ohuruogu who was crowned 2008 Olympic champion in the women's 400 metres announced she is retiring on Saturday.

The 34-year-old -- who indicated last year this season would be her last -- failed narrowly to defend her Olympic title in London in 2012, taking silver behind great rival Sanya Richards-Ross.

Ohuruogu -- also won the world outdoor title on two occasions in 2007 and 2013 -- had to battle to even compete at the 2008 Olympics in Beijing.

She was handed a one-year ban for missing three out-of-competition drug tests in 2006 with a British Olympic Association (BOA) bylaw dictating that any doping offences were punishable by lifetime Olympic bans.

However, despite losing her case at the Court of Arbitration for Sports (CAS) she found an unlikely saviour as the BOA allowed her appeal in November 2007 citing "significant mitigating circumstances".

"Today is the start of the British Championships and, as I won't be there competing, I feel it is a good time to formally announce my retirement from competitive athletics," she said in a statement posted on her website.

"I didn't feel ready to retire after last season but a combination of my studies and a niggling injury restricted how much training I was able to do this year."

Ohuruogu, who is studying for a law degree, only took up athletics so she could use it to help her improve her netball skills.

"Athletics has been my passion for so long and I am proud to call myself an athlete," she said.

"I love the diversity of the events and the brilliant characters that come from them.

"I end my career with four Olympic medals and five World Championships medals.

"I have truly met some wonderful people over the last 15 years, competing around the world, and I am blessed to call many of them friends."