Nicole Scherzinger and Lewis Hamilton have split up.

The 'Boomerang' singer and the Formula 1 racing driver - who have been dating on and off for five years - have reportedly called time on their relationship after their hectic work schedules meant that they hardly spent any time together as a couple.

Nicole - who is based in the US - has just reclaimed her seat on the 'The X Factor' UK judging panel and is currently dashing around the country for auditions, while Lewis - who lives in Switzerland - has been focusing on his racing career and has been competing around the globe.

A source told The Sun newspaper: "It's so hard to keep up a relationship when they're barely in the same country as each other.

"Both have supported each other in their careers and will continue to do so. But the nature of their work ultimately cost their relationship."

The split comes just two weeks after the 28-year-old star hinted that he wanted to propose to the brunette beauty within the next year.

He said previously: "We've been together for five years, which is quite a milestone really.

"But hopefully [I'll propose] in the near future before we get to six years."