MILEY CYRUS has issued a stern warning to fiance Liam Hemsworth’s wild-child co-star Emma Roberts: “Hands off my man!”

Her Australian fiance has been filming “Em­pire State” on location in New Orleans and New York with Emma, who plays his love interest. Now Miley is terrified that the hard-partying niece of Oscar winner Julia Roberts is trying to steal her sweetheart!

“Miley’s become super-protective since she and Liam got engaged,” said an insider. “She’s worried that while he’s off making movies with hot women, he’ll be tempted to cheat.

And it didn’t help that Emma showed up on set declaring that she is sin­gle and ready to mingle.”

Miley, 19, and Liam, 22, announced their engage­ment in late May after three years of dating. And while Miley has visited Liam on-set in New Orleans and he’s traveled back to Los Angeles recently to see her, insiders say that she blew up after learning that the “Hunger Games” hunk had been hanging out with Emma, 21, and another co-star, actress Nikki Reed, during off-work hours.

“Miley doesn’t want Liam socializing with a loose cannon like Emma,” the in­sider divulged. “She thinks the girl is bad news. Not only did she tell Liam it had to stop, she even confront­ed Emma, reminding her that Liam is off the market. Miley more or less said, ‘Hands off my man!’”

But Emma apparently isn’t con­cerned.

“She couldn’t care less what Miley thinks,” added the source.

“She makes fun of Miley behind her back, saying she’s just a washed-up tween star. Emma feels she has nothing to lose, so she’s pushing it as far as she can with Liam. And he’s definitely enjoying the attention.”