Martin Bashir

Martin Bashir is leaving ABC News' Nightline to anchor an MSNBC show.

Besides hosting a daily afternoon program on MSNBC starting in September, he'll become a regular contributor to NBC's Dateline.

In a statement Thursday, MSNBC President Phil Griffin called Bashir's work "smart, original and thoughtful," adding that he "couldn't be happier to bring someone of his caliber to the network."

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"I am absolutely delighted to be joining MSNBC and NBC," Bashir said in a statement. "This is a rare and special opportunity  —  to host a daily news and current affairs show and also work on long-form journalism. ... This is an enormous privilege and I cannot wait to get started."

Bill Weir, who co-anchors the weekend edition of Good Morning America, will replace Bashir on Nightline, joining co-anchors Terry Moran and Cynthia McFadden.

Bashir joined ABC's 20/20 in 2004. A London-born journalist, he rose to fame with documentaries including Living with Michael Jackson, which aired on ABC in 2003, and an exclusive interview with Princess Diana in 1995.