Rio Olympics 2016: Usain Bolt's girlfriend Kasi Bennett is aware of infidelity

Jamaica's Usain Bolt celebrates as he crosses the line to win gold in the 2016 Olympics men's 100-metre final. Photo / AP

Usain Bolt's main squeeze back home will be upset - but won't think he crossed the line for a series of post-Olympics romps in Rio, the track superstar's sister predicted.

Christine Bolt-Hylton, 32, defended Bolt for celebrating his 30th birthday by making out with a brunette, twerking with another and then vaulting into bed with a third - who posted racy images of their tryst online.

"I'm sure Kasi will be used to it by now. She is used to seeing pictures like this," Bolt-Hylton said of Kasi Bennett, the star's Jamaican girlfriend of two years whom she believes he'll marry.

"People ask for pictures with him and he is always willing to have pictures. She is used to him being in the public domain," she said, according to The Daily Mail.

Brazilian beauty Jady Duarte, 20, shared images over the WhatsApp chat app of herself canoodling with Bolt in his Olympic Village room.

"I don't think anything happened between him and the Brazilian girl," Bolt-Hylton added.

"He loves Kasi too much to jeopardise the relationship. I'm looking at the pictures and it doesn't look like he was doing anything with her."

Bolt and Bennett have reportedly been an item an item for more than two years.

Usain Bolt.
Club Alin Rio, 2016.
After conquering the world with the triple triple...https://t.co/1MHm8ZrTDb

— Ebuka Obi-Uchendu (@Ebuka) August 21, 2016

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Asked if Bennett will be upset, Bolt-Hylton said: "The pictures are of a young girl. I know she will be upset. But she will talk to him and I know they can work their difficulties out.

"Usain doesn't believe in cheating. ... He has never done this before as far as I know," she added. "When he was much younger he was popular with the girls but from when they have been together, he hasn't done anything like that."

Bolt should still apologise to Bennett for the bedroom pictures with Duarte, his sister said - adding that "Kasi was definitely OK" with the pictures that emerged from the private party at All In, a club in the Barra de Tijuca suburb of Rio de Janeiro.

Adding to the embarrassment, it emerged that Duarte was the widow of a Rio drug lord, Douglas Donato Pereira, known as Diná Terror, with whom she had two children.

Meanwhile, Bolt's one-track mind was still evident Monday, when he was photographed with several scantily clad women at a London hot spot, The Mirror reported.

He set hearts racing at the Cirque le Soir club, where he took to the stage and serenaded his fans.

"We gave him the mic and he was telling everybody it had been his birthday a couple of days ago," Yvette, a waitress at the club, told the Daily Mail.

"From about 1 until 3am, people were buying him drinks - champagne, Sex on the Beach, Kamikaze shots - everybody was just appreciating him and celebrating his gold medals," she said.