Clooney's official spokesperson recently emphatically denied published reports that the couple have ended their relationship after a year together.
Keibler has now spoken out about the rumours while attending a public event in New York City.
"It's all nonsense," she told Access Hollywood, adding: "I don't even know where they come up with that."
Keibler previously praised Clooney as a perfect boyfriend because of his sense of his humour.
"I was actually not really searching for a boyfriend. I don't think about that. I live in the present moment. That was my New Year's resolution... and it's worked out pretty good so far," she also said last autumn.
The duo were first linked in August 2011, when Keibler was spotted at Clooney's vacation home in Lake Como, Italy.
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