Timberlake to join Shrek 3 cast

Timberlake has embarked on an acting career

Pop singer Justin Timberlake is joining the cast of the next Shrek movie, teaming up with his actress girlfriend Cameron Diaz.

Timberlake, 24, will voice the new character of Artie, the rebellious nephew of King Harold, producers Dreamworks revealed.

Diaz, 32, has played Princess Fiona in the two previous animated adventures.

Shrek has become one of the biggest cartoon movie franchises, taking $708m (£369m) at the US box office alone.

The first film, which introduced Mike Myers as the voice of the green ogre Shrek, won an Academy Award in the best animation category in 2002.

Timberlake and Diaz are considered one of Hollywood's hottest couples

The films have also featured the voices of Eddie Murphy as Donkey and Antonio Banderas as Puss in Boots.

Banderas has signed up for a Shrek spin-off, with Puss as the lead character.

In the third film, it will be the job of Shrek to teach Artie to act like royalty.

Although Timberlake is best known for his pop career, starting out with boy band N'Sync, he has recently embarked on a film career.

He stars alongside Kevin Spacey and Morgan Freeman in the forthcoming Edison, playing a journalist who uncovers corruption.

He will next be seen in Alpha Dog, a movie about drug dealing.