01/14/2009 AT 04:40 PM EST
Law & Order: SVU
is back in production, but sources tell PEOPLE that the show's lead actress, Mariska Hargitay, who suffered a partially collapsed lung
during the show's holiday hiatus, has not yet returned to work.
On Monday, the star's rep released a statement saying "Mariska Hargitay has been sidelined with a pneumothorax (a partially collapsed lung)," adding that in spite of her condition, the 44-year-old actress "will appear in all episodes for the rest of the season of Law & Order: SVU
The rep has not said why Hargitay hasn't returned to the set, or given any indication how long her illness will keep her away.
A production source tells PEOPLE that the show has had to rearrange schedules to accommodate the star's absence. "We don't know when she'll be back to production," says the source. "We're just going to wait and see." But, the source adds, as long as she returns in the next couple of weeks, "she won't miss any episodes. They'll work around her."
In the meantime, the crew has remained busy shooting portions of episodes featuring the return of actress Stephanie March. But sources say there is a limited amount of shooting they can do without Hargitay.
While neither NBC nor Hargitay's personal rep have released details as to what caused the collapsed lung, her SVU
co-star Richard Belzer said today on The View
that the actress "had a little accident sledding," which Hargitay's rep denies.
"She's absolutely okay," Belzer added. "She's doing really great."
An NBC spokesperson tells PEOPLE, "Mariska is feeling better. We are looking forward to her quick recovery and return to set."
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