Janet Jackson has married her billionaire fiancé in secret.

The I Get So Lonely hitmaker, who got engaged to Wissam Al Mana in 2012, finally squashed rumours that they were planning an extravagant wedding by revealing that they had already tied the knot.

"The rumours regarding an extravagant wedding are simply not true. Last year we were married in a quiet, private, and beautiful ceremony," the couple said in a statement to Entertainment Tonight.

"Our wedding gifts to one another were contributions to our respective favourite children's charities. We would appreciate that our privacy is respected and that we are allowed this time for celebration and joy."

Speculation has been feverish that their wedding had been delayed over a pre-nup and that there were plans to fly their families to Qatar for a lavish Muslim wedding in the spring.

One report claimed that Jackson would walk away with half a billion dollars if she and Al-Mana divorced.

The 37-year-old billionaire businessman, who is the managing director of Al Mana Retail, which represents A/X Armani Exchange and has major shares in Saks Fifth Avenue, was said to have torn up the pre-nuptial agreement his lawyers had designed to protect his fortune.

A source said: "Janet will be marrying into the sort of wealth not even her brother Michael managed to amass during his lifetime of success. She's looking forward to a fairytale life with Wissam.

"After two failed marriages, she deserves it."

The 46-year-old singer, who is the sister of the late Michael Jackson, was previously married to singer James DeBarge and to director René Elizondo Jr. She was also in a seven-year relationship with music producer Jermaine Dupri.