Hollywood couple Charlize Theron and Sean Penn are reportedly planning to adopt.

They are said to be moving in together and the actress is eager for her son Jackson, 2, - also adopted - to have a brother or sister, reports femalefirst.co.uk.

"Charlize was an only child and always wished for a brother or sister. It's important to her that Jackson have a brother or sister," said a source.

Penn, who has a daughter Dylan, 23, and son Hopper, 20, with his ex-wife Robin Wright, is reportedly particularly keen to adopt from Haiti, the island where he has done charity work since it was hit by an earthquake in 2010.

"Sean is passionate about Haiti. He's done a lot of work there and thinks adopting from Haiti makes sense. They hope to adopt by the end of the year," said a source.