Kate Hudson's brother has poked fun at Hollywood gossip after spotting a magazine cover claiming the actress had moved in with Brad Pitt.

Oliver Hudson, who starred in CBS comedy series Rules of Engagement and the ABC drama series Nashville, posted a picture of Star magazine on his Instagram with a lengthy caption detailing life with his rumoured new brother-in-law.

The cover was a composite of Kate Hudson and Pitt next to one another, along with a photo of a moving van and the headline: 'It's Getting Serious... BRAD MOVES IN!'

A quote claiming to be from Hudson's mother Goldie Hawn read: "He makes my daughter so happy!"

"Yeah and it's been hell!" Hudson wrote. "He's messy as s**t! He drinks out of the f***ing carton and leaves the door open when he's taking a dump!! And this is when he's at MY house!!

"He's already calling me brother and has driven a wedge between myself and my real brother Wyatt who now won't speak to me.. he insists my kids call him uncle B and lost my youngest at the Santa Monica pier for 2 days.. thank god for amber alert.. my mom's overtly flirting with him! Shes wearing these little nighties around the house now?! But ALL DAY!! Like at 3pm!

"And Pa just keeps saying “All right!! It's Brad Pitt!!” Anyway not going well.. so BP.. it's time to move out man.. I need my life back dog.. I'll smoke one more bowl and then get the fuck out.. we thank you.. oh and I found your medical bracelet so I'll get that back to you.. ok.."

Kate Hudson has not responded to rumours that she is dating Pitt, and her mother laughed when asked about it by paparazzi as she was leaving a supermarket.