Dutch rider Lars Boom has won a chaotic fifth stage of the Tour de France marked by the withdrawal of defending champion Chris Froome following two crashes.

A day after hurting his left wrist in a crash in the fourth stage, Froome fell again early on the 152.5-km route from the Belgian town of Ypres to Arenberg-Porte du Hainaut in France on Wednesday, scraping his right side.

Then, just before the first patch of cobblestones about halfway through the treacherous route, the Team Sky rider took another spill. With a cut under his right eye, he limped over to a team car, climbed in and left the race.

The team wrote on Twitter after his withdrawal: "Heartbreak for Chris Froome after another hard crash.''

Riders were flying left and right on the difficult stage, and one even hurtled head-first over his handlebars on a cobblestone patch.

Marcel Kittel of Germany, the winner of three of the first four stages, also went down. Belgian Juergen van den Broeck and American Andrew Talansky crashed, as well, but they remained in the race.

The withdrawal of Froome, the main pre-race favourite, leaves the three-week cycling showcase wide open.

Italy's Vincenzo Nibali is wearing the leader's yellow jersey, but two-time champion Alberto Contador is only two seconds behind and could become the man to beat.

Source: AP