Tim Westwood has been axed as Radio 1's voice of rap after nearly 20 years on the station.

The 55-year-old award-winning broadcaster is leaving as part of a scheduling shake-up designed to attract younger audiences. He began his career at Radio 1 in 1994 as host of the station's first rap show.

The new line-up will start with MistaJam at 7pm, followed by Charlie Sloth at 9pm and DJ Target at 11pm.

Ben Cooper, Radio 1 controller, said: "I'd like to thank Tim for the last 20 years on Radio 1. His passion for hip-hop is legendary. I wish him all the very best."

Westwood, who is the middle-class son of the former Bishop of Peterborough, is credited with introducing generations of listeners to the latest developments in hip-hop.

In 2006 David Cameron accused the DJ of encouraging knife and gun crime and his adopted "street" patois, which is said to have partly inspired Sacha Baron Cohen's comic creation Ali G, often divided listeners.

However, his connection with stars including Public Enemy and Jay Z, who respected his knowledge of the industry and influence over fans, meant that he delivered many exclusives for the BBC.

The revamped Radio 1Xtra schedule will take effect from 21 September. Westwood has not commented on his departure.