Nick Jonas threw his beauty queen girlfriend Olivia Culpo into a "full panic" when he dropped to one knee and appeared to prepare for a proposal during a live TV performance on Sunday (25Jan15).

The former Jonas Brothers star took to the stage to sing at the Miss Universe pageant in Miami, Florida and he took a moment to serenade his partner, who won the competition in 2012, as she was sitting in the audience.

At one point, Jonas dropped to one knee, and he has revealed his romantic gesture led Culpo to believe he was about to pop the question to her during the live TV broadcast.

He tells Britain's The Sun newspaper, "I went down and sang to her and I got on a knee and sort of approached her. Her face was in full panic - she thinks I'm going to propose on national TV in front of the whole world!... We're 22, so there's plenty of time to do that. We're very happy."