"[Moffat] needs enough time to get that done and then start work on the next series of 'Doctor Who,'" BBC One controller Danny Cohen said at this week's Church and Media Conference in Derbyshire. "So there will be ['Doctor Who'] episodes, but not as many."
The British broadcaster recently announced it had renewed the mystery series "Sherlock" for a second season.
It also confirmed last week it had ordered a fresh run of episodes of the long-running science-fiction show "Doctor Who," although it did not say whether all of the installments would air in 2012.
"There will be some episodes, but there won't be a full series, so we won't have a 13-part run," Cohen said at the conference. "There's only so many hours a day [Moffat] can be awake. The man has to sleep and eat, and he's got a family. ... Steven Moffat is the creative driving force behind 'Doctor Who.' He also, rather magically at the same time, created and got to air 'Sherlock.' So we have to get that balance right. There'll be more episodes again in 2013, for the 50th anniversary of 'Doctor Who.' So that's a big year."