Sir Mick Jagger has become a great-grandfather.

The Rolling Stones frontman's granddaughter Assisi Jagger has given birth to her first child, a baby girl, with boyfriend Alex Key, according to Britain's HELLO! magazine.

Assisi is the 21-year-old daughter of Jade Jagger, Mick's 42-year-old offspring, who is also expecting a baby boy next month.

The new mother recently said: ''The women in our family just tend to have children young, it runs in the genes.

''I grew up quite quickly and wouldn't have considered having a child if I was doing what my friends are doing at this stage, messing around. I don't drink, I don't smoke and I'm very settled.''

However, Assisi admits her 70-year-old grandfather - who recently mourned the death of his girlfriend L'Wren Scott - is unlikely to enjoy being reminded of his age by welcoming a great-grandchild.

She said: ''I imagine it's nice to be a great-granddad - although I'm not sure he likes the idea of getting old, or being called one.

''I call him Mick - I wouldn't start calling him grandpa.''