Since last summer, when Britney Spears' pal Sam Lutfi appeared out of nowhere, the 33-year-old so-called film producer has become an integral part of the pop singer's life.

He's called Ryan Seacrest's radio show to denounce rumors that she's pregnant, organized her 26th birthday party and stayed overnight at her homes — platonically.

But in the the current issue of Us Weekly, there may be good reason for concern.

Lutfi has had two restraining order against him for violent verbal and physical attacks, according to complaints obtained by Us, and has gone by multiple aliases, including Osama N. Lutti and Osamah N. Lutfi.

In a 2005 complaint, Jumana Issa, a business acquaintance, claims Lutfi "harassed me repeatedly with obscene e-mails, offensive faxes, telephone voice mails (around 1 a.m. to 3 a.m.), out-of-control behavior and outrageous telephone hang-ups (around 15 to 30 a day)." In one fax, Lutfi scolded: "Peel yourself away from all the candy ... and overhangin [sic] belly ... and answer my e-mails."

His former neighbor, Douglas Snoland, filed a similar complaint in 2004, alleging that Lutfi tried to kick down his front door when he suspected Snoland of having his car towed. Snoland also accused Lutfi of wanting to kill his 73-year-old disabled mother. In the complaint, Snoland accused Lutfi of saying: "I will beat your *** ... Your mother is a f-----g old hag. You are a f----t. You will regret the day you ever met me." Lutfi’s attorney denied the threats, but a judge granted a three-year restraining order to Lutfi to stay at least 15 feet away from Snoland and his mom.

As for his past work history, he is listed as a producer of the 1998 B-movie Bug Buster on imdb.com. The movie's actual producer and director, Lorenzo Doumani, says Lutfi was his $350-a-week assistant. "He was a hustler type, a fast-talking kid," recalls Doumani.

Now Spears' pals worry he is in her life under false pretenses. "They are frightened," a source close to her parents, Jaime and Lynne, tells Us. "They know she is being taken advantage of."

"She's so desperate for a friend that it's easy once you get in there," adds a pal.