LOS ANGELES (Reuters) - Newscaster Paula Zahn will leave CNN next month after nearly six years at the cable network to make way for a new prime-time program hosted by freshly hired former NBC News correspondent Campbell Brown.

The departure of Zahn, 51, who first appeared on CNN on Sept. 11, 2001, was confirmed by CNN-U.S. President Jon Klein on Tuesday, a day after he announced the hiring of Campbell, while refusing to say whose time slot she would be given.

Zahn's exit was not unexpected. Her show, "Paula Zahn Now," has struggled in the ratings behind not only Bill O'Reilly on the Fox News Channel, but also MSNBC's "Countdown with Keith Olbermann" and "Nancy Grace" on CNN Headline News.

In an e-mail circulated to CNN staff and later the media at large, Klein said the last "Paula Zahn Now" telecast would air on Aug. 2.

Zahn said in an accompanying message that she planned to "take a break between jobs and catch my breath before I take on my next role."

She will be replaced initially by various substitute hosts leading up to the November launch of a new program anchored by Brown, who worked for NBC for a decade as White House reporter, fill-in anchor for Brian Williams and host of "Weekend Today."

Brown, 39, told reporters on a conference call on Monday that she expected to be on CNN's air for just over a month before going on maternity leave in December to have her baby. She said she hoped to be back by early February, in time to help cover the U.S. presidential primary elections that month.

Zahn was a 10-year CBS News veteran when she joined Fox News as an evening news anchor in 1999. Fox fired her in September 2001 after learning she was in talks to anchor a news program on rival CNN for more than $2 million a year.

She ended up making her debut on CNN during coverage of the suicide hijacking attacks on New York and Washington.

Four months later, CNN was embarrassed by the airing of a promotional spot, which the network said was run without approval of top executives, touting its new morning newscaster as "just a little sexy."

CNN is a unit of Time Warner Inc. Fox News is owned by News Corp. MSNBC is part of NBC Universal, which is controlled by the General Electric Co.