Madonna's older children are more "challenging" to parent.

The 'Like A Virgin' hitmaker - who has Lourdes, 20, Rocco, 17, Mercy, 11, David, 11 and five-year-old twins Stelle and Estere - admits it is tougher looking after her older kids as they need more "guidance" as they transition into their adult years.

She said: "Lola has a different father than Rocco, and I have four adopted kids, so there's a lot of outside influences. I'm trying to make sure I impart the same wisdom and love to everyone.

"I had this funny notion that when your children get older, they learn to take care of themselves and it gets easier. But actually, the older they get, the more challenging it gets - because now they're becoming adults, and they really need guidance."

And the 59-year-old singer has confessed she is the "bad-cop" in her children's eyes.

She told People magazine: "I'm bad-cop, I'm the one that says no. I accept that role. I'm not the popular parent."

Meanwhile, Madonna previously revealed she was told she was "not fit to raise children" when she tried to adopt her daughter Mercy James.

She said: "I met Mercy soon after I met my son David, but they were living in different orphanages. David was in Mchinji in Home of Hope, and Mercy was here in Blantyre at Kondanani. Mercy was suffering from malaria, and David from pneumonia. And when I held each of them in my arms, I whispered in their ears, that I would look after them. And I promised them that they would grow up into strong and healthy adults.

"I was granted permission to adopt David first. And some time later, I filed a petition to adopt Mercy. But this time, the judge who was presiding said no. I was recently divorced, and she informed me, as a divorced woman, I was not fit to raise children and that Mercy James was better off growing up in an orphanage."