Sanders wins Democratic caucus in Kansas

Bernie Sanders defeated Democratic frontrunner Hillary Clinton in a caucus held on Saturday in the heartland state of Kansas, giving a boost to his flagging campaign, US media reported.

"It's official: @BernieSanders takes Kansas," read a tweet sent by Kansas Democratic party officials.

The Vermont senator had lost significant momentum to the former US secretary of state following last week's Super Tuesday vote, after which Clinton gained a sizeable lead in the count for delegates needed to secure the Democratic nomination.

Sanders lost no time crowing about the victory, and using it in a fundraising appeal sent around to his supporters via email.

"Tonight's victory means the last three states called in this Democratic primary have been won by our political revolution," Sanders wrote.

"And we're optimistic that we'll do well in the caucus already under way in Nebraska, and another in Maine tomorrow," he wrote.