Russell Brand: Styles is an apprentice womaniser

Russell Brand has referred to Harry Styles as his "womanising apprentice".

Both stars are known for being ladies' men and for dating numerous famous females in the past.

Harry, 19, causes mass hysteria with his One Direction bandmates and has been linked to the likes of Taylor Swift and Cara Delevingne.

Russell has a past with substance abuse and is currently working on a petition to get UK drug laws changed.

The British comedian decided to call on his trusted friend for help.

"My adored womanising apprentice @Harry_Styles please encourage your followers to sign this... one day you might need it! (sic)" he posted on Twitter.

Russell has abstained from drug use since 2003 and is also a patron of addiction charity Focus 12.

The star has been busy tweeting about his latest initiative and is using his humour to gather signatures.

"Hello. Do you know anyone who has a drug problem? Have you seen anyone with one? Could we improve their treatment?" he wrote.

"Please sign this thing. It will help is all. It will take 90-100 seconds (depending on typing skills) (sic)."

Meanwhile, Harry and bandmates Zayn Malik, Louis Tomlinson, Liam Payne and Niall Horan have revealed they will be penning a book about their lives.

One Direction: Where We Are: Our Band, Our Story will hit stores in August, shortly before the release of their hotly-anticipated 3D movie.