Justin Bieber has written a song for his mum.

The 18-year-old singer is very close to his mother, Pattie Mallette, and gave her the ultimate early birthday gift by recording a tune on her honour.

After a day out with her famous son, Pattie wrote on her twitter page: Had the BEST mother-son date ever w @justinbieber. Dinner & a movie & gave me & early bday present - he wrote me a song!#MomentsToCherish. (sic)"

Justin responded: "love u (sic)"

While he is incredibly close to his mum, Justin also has another lady in his life, Selena Gomez, and he has said he refuses to hide his relationship with her.

The couple - who first started dating in 2010 - are often photographed holding hands or enjoying quality time together, and the 'Baby' hitmaker believes it would be "unhealthy" to have it any other way.

He explained: "There's no way to hide the relationship completely, because then it would be unfair to us.

"It's like, 'You take this car, and I'll take this car, and then we'll meet up at the spot. Then, you go in this door, I'll go in this door. We'll end up crossing ways. You get back in this car. We'll cross over, do a James Bond. You go through the kitchen. I'll go through the back area. Then we'll meet in the dressing room and see each other'.

"At that point, it's not even a relationship. You're just hiding from everyone. That's unfair and unhealthy."