Former Dannii Minogue and model Kris Smith have parted company after four years together.

The couple, who are parents to a 21-month-old baby boy, both confirmed the split via Twitter.

Early this morning, Dannii wrote: "It brings me great sadness to tell you that Kris and I have separated. We still care for each other and ask for privacy at this difficult time, in particular for our son Ethan who remains our number one priority."

She later added: "Hi Tweet peeps. Needing to retreat for a while. Thank you for your ever loving continued support."

Smith also took to the micro-blogging site to confirm the news, tweeting: "Dannii and I have a deep mutual love and respect for each other and although things have not worked out we have a gorgeous son together that we both love and implore everyone to respect our privacy at this challenging time."

Reports today suggest that rumours of infidelity on Smith's part resulted in months of tension between the pair.

The Daily Mail quotes a friend of Dannii's as saying: "It's so sad, because Dannii gave up so much for Kris. Part of her decision to leave the UK and move full time to Australia was because of his insistence that his career was in Australia... It was all about Kris.

The source added: "Dannii really didn't want to give up on them, but there comes a point when you have to admit defeat."