The singer and actress was photographed wearing what was originally reported to be a large diamond ring at Muhammad Ali's Celebrity Fight Night in Arizona over the weekend, sparking rumours that the couple were engaged.
> Liam Hemsworth on Miley Cyrus: 'She really makes me happy'
However, Cyrus wrote on her Twitter account on Monday (March 26): "I'm not engaged. I've worn this same ring on this finger since November! People just wanna find something to talk about! It's a topaz, people!"
Hemsworth and Cyrus met on the set of Nicholas Sparks drama The Last Song during 2009 and began dating after finishing work on the film. They are thought to have broken up briefly during autumn 2010.
Hemsworth is currently appearing in The Hunger Games alongside Jennifer Lawrence and Josh Hutcherson.
Cyrus, who recently injured her tailbone during a fall at home, will soon be seen in comedy-drama LOL, which will receive a limited release on May 4 in the US.
The movie opens on June 1 in the UK.
Watch Miley Cyrus in the trailer for LOL below: