London, March 29 (IANS): Kell Brook retained his IBF welterweight belt as he forced Romanian challenger Jo Jo Dan to throw in the towel after fourth rounds and four knockdowns on Saturday, a media report said on Sunday.

The Briton remained unbeaten after his 23rd knockout win in 34 fights.

Dan was floored twice in the second round and twice more in the fourth at the Motorpoint Arena in his hometown of Sheffield.

Brook won the IBF title by beating America's Shawn Porter last August, and he defended the belt against Canada-based Dan at the Motorpoint Arena in his hometown of Sheffield.

Victory paves the way for a more lucrative fight this summer, with Brook targeting the likes of Juan Manuel Marquez, Marcos Maidana.

Brook returned from an horrific knife attack last year to defend his title.

Only six months ago, Brook was attacked on holiday in Tenerife, stabbed in the thigh with a machete by an assailant yet to be caught. He needed 60 stitches.