The chief executive of privately owned educational publisher Houghton Mifflin Harcourt has resigned, the company has confirmed.

In a statement, the company said Barry O'Callaghan, who assumed the post in April 2009, was leaving to pursue other ventures. He will remain as senior advisor to the company.

Chief financial officer Michael Muldowney wil take over until a permanent candidate is found, spokesman Josef Blumenfeld said.

Houghton Mifflin, whose authors include Philip Roth and which also publishes the Curious George children's books, has been moving more into educational services, such as school district consulting and teacher development, Mr Blumenfeld said.

Additional reporting: Reuters