Steve Bell will leave Twentieth TV after just a year as president of the Fox Inc. network production division and will instead head a new movie and miniseries production unit, Foxstar Prods., at the studio.

Peter Roth, who joined Twentieth at the same time as Bell last May — part of a division shakeup instituted under then-Twentieth chairman Lucie Salhany — will move from president of production to president, heading the unit and assuming Bell’s responsibilities.

Bell takes a multiple-movie commitment from Fox Broadcasting Co. to Foxstar, where Salhany is now chairman, and is charged with developing and producing movies for Fox’s soon-to-be-launched basic cable service as well as other broadcast outlets.

The operation, which Bell said will have its own small staff, will be separate and distinct from Fox West Pictures, the unit principally responsible for producing (as well as acquiring) movies for Fox Broadcasting.

The switch comes shortly after the selling season for 1993-94 and follows a somewhat rocky year at Twentieth, which endured a public feud with several cast members on “In Living Color” as well as another midseason production change on its long-running NBC drama “L.A. Law.”

Twentieth sold one new series for next fall to Fox, “The X-Files,” which joins returning shows “Law,””Living Color,””The Simpsons” and “Picket Fences.”

Bell acknowledged that the year had been “a tough one,” citing “explosive changes” in the network production business. He added that he yearned to have a greater opportunity for a hands-on production role and that Salhany — who has stated that Fox must ultimately control its own destiny in terms of supplying programs — also has a need for longform product as the weblet rolls out “Fox Night at the Movies” as a regular weekly addition to its schedule.

The former senior VP-general manager of Tribune-owned independent station KTLA, Bell was involved in such syndicated productions as “To Catch a Killer” and “Voyage of Terror: The Achille Lauro Affair” in that capacity; still, he acknowledged that the luxury of having two presidents within Twentieth is difficult to justify “in a business that’s not that profitable.”

Roth, previously president of Stephen J. Cannell Prods., is an established production executive, and Fox said it expects him to move seamlessly into the new post.

The new regime at Twentieth was encumbered from the start, according to some observers, after Salhany held a series of meetings with top talent agencies last summer seeking to lay down new ground rules on costs. In those sessions Salhany preached the need for greater frugality — a generally accepted truth that nevertheless prompted many reps to say they would simply advise their clients to go elsewhere.