The U.S. Justice Department will pursue vigorously its antitrust lawsuit against Apple and two publishing houses over allegations that they conspired to fix prices for electronic books, the head of the agency's antitrust division, Sharis Pozen, said on Thursday.

The department settled with three other publishers who were accused of participating in the alleged scheme, and they will have to end their most-favoured nation agreements with Apple and other e-book retailers, U.S. Attorney Eric Holder said.

(Reporting by Jeremy Pelofsky; Editing by Lisa Von Ahn)