National Public Radio chief executive Ken Stern is stepping down after a disagreement with the network's board of directors over the direction of the U.S. broadcaster.

Stern was with the network 10 years as chief operating officer and chief executive and was credited with improving its financial health and managing the network during a period when its weekly audience doubled from 13 million to 26 million listeners.

The NPR board of directors issued a statement Thursday saying Stern was leaving by "mutual agreement."

"During his tenure, Ken was instrumental in improving NPR's financial health and for initiating important work extending NPR's reach to various new platforms including satellite and digital distribution," said Howard Stevenson, the board's vice-chairman.

"Under his watch, NPR News significantly increased the number of staff, foreign and domestic bureaus and areas of coverage."

However, the Washington Post reports the board declined to renew his contract.

Station managers, who comprise 10 members of the board, believe Stern did not do enough for the hundreds of public stations that pay dues annually to NPR.

They have said new media initiatives, including extensive podcasting and a growing website on NPR, are taking resources that should go to regional stations.

Board chairman Dennis L. Haarsager will serve as interim CEO while the board searches for a permanent replacement.

NPR staff based in Washington, D.C., said they were shocked by news of Stern's departure.

Stern is the latest in a string of high-level departures at NPR, including Bill Marimow, NPR's vice-president for news, and Barbara Rehm, NPR's managing editor for news.

Stern, 44, had worked with former CEO Kevin Klose at Radio Free Europe and was hand-picked by Klose as his successor.

He also is a past director of the U.S. International Broadcasting Bureau in Washington and was deputy general counsel for then President Bill Clinton's 1996 re-election campaign.