Mariah Carey and Nick Cannon are being sued by their former nanny.

DaCosta, who was hired as a full-time nanny by the estranged duo when their children were infants, claims the 44-year-old singer became jealous when she developed a very close relationship with them.

She also alleges that she was overworked and sometimes forced to look after the twins for more than 100-hours a week.

DaCosta is seeking back pay and other damages, according to gossip website TMZ.com.

Mariah admitted last February that she regularly fired nannies for interfering with the bond she has with her children.

She said at the time: "Unfortunately I have to have nannies but I've very hands-on. I fire nannies like this and I hate doing it, but I have to because if they try to make themselves more important in the baby's mind than me..."

Nick also confirmed in April that the singer fired their children's minders "every other week."

He explained: "It's something about a woman and her children...you know, the minute the child chooses to go to the nanny before they go to the mom -- I would have an issue with that, too.

"Everything's on a trial basis. It's just like, hey, we're gonna see how this works out. And we're always traveling, so the nanny might not get a plane ticket to the next city."