Christiane Amanpour, television's best-known international correspondent, said Thursday she's ending her part-time stint at CBS' "60 Minutes" (search) because the arrangement had "run its course."

Amanpour is continuing as chief international correspondent for CNN (search).

She had been contributing to "60 Minutes" since 1996, usually four or five stories a year. This season she's done two: a profile of Ukrainian President Viktor Yushchenko, and a story about how the U.S. military sent a psychology unit to Iraq to help deal with battle fatigue.

The arrangement with "60 Minutes" "allowed me to report in-depth international stories for a large and important American audience, a mission I am dedicated to," she said in a statement. "But I have concluded this unique arrangement has now run its course and therefore I have decided not to seek a renewal of my contract with `60 Minutes.'"

Reached in London, Amanpour would not elaborate on her statement. People close to her have said she's concerned that the type of hard-hitting international stories she's done are not valued as much at "60 Minutes" as they were under founding executive producer Don Hewitt.

Jeff Fager (search), the show's current executive producer, said that was a distortion.

"I think she's a very classy correspondent," he said. "She's smart. She's done terrific work over a long career."

There's some question whether CBS News would have even sought to renew her contract. Scott Pelley and Bob Simon have recently become much more active as "60 Minutes" correspondents, and they have a keen interest in international stories as well.

There's also doubt about the future of the Wednesday edition of "60 Minutes" — and if it were canceled it would leave more CBS News reporters trying to get stories on "60 Minutes," including Dan Rather.

Hewitt said that he'd never worked with a better reporter than Amanpour, "and I've worked with Edward R. Murrow, Walter Cronkite and Eric Sevareid."

"She's a great reporter," he said. "She's brave beyond bravery. I mourn the loss."

Hewitt wouldn't comment about Amanpour's current relationship with CBS News, but said, "if I were there, she'd be there."

The most recent story Amanpour completed for CBS, a profile of filmmaker Ridley Scott, ran on "CBS Sunday Morning," not on "60 Minutes."

"60 Minutes" is television's first and still most-popular newsmagazine, and an on-air role is such a golden gig that leaving one is like quitting the Rolling Stones. The last correspondent to leave "60 Minutes" was Meredith Vieira in 1991.