Colin Murray and Edith Bowman takeover at the end of March

Radcliffe and Riley, aka Lard, are leaving Radio 1 on 26 March for slots on Radio 2 and 6 Music.

Vernon Kay will present weekend morning shows, while Scott Mills will fill in for drivetime DJ Sara Cox, who goes on maternity leave in May.

Murray and Bowman were involved in the launch of Channel 4's short-lived morning show Rise last year.

While their association with Rise only lasted a few months, they have been a success in Radio 1's Saturday and Sunday morning shows.

"These changes have come about as a result of Mark and Lard leaving the network and Sara Cox going on maternity leave," said a BBC spokesman.

"This has allowed us to bring some fresh young talent to daytime on Radio 1 in the weekdays and expand the roles of some newer talent at the weekend."

Sidekick

Murray and Bowman joined Radio 1 in March 2003 when they took over the Saturday morning slot, then hosted by Mills.

Mills, 26, currently fronts a weekend afternoon show. He joined the station from London's Heart FM in 1998.

Cox has presented the weekday drivetime show after being moved last year from the breakfast show to make way for Chris Moyles.