World News Update, what you need to know

Kevin Rudd faces an uphill battle to nudge Helen Clark out of the way and become United Nations secretary-general, but he should not be counted out, says one the UN's best known analysts.

ELSEWHERE:

WUERZBURG - A man has seriously injured several people in a stabbing attack aboard a train in Germany.

CLEVELAND - The Republican National Convention is in uproar after opponents of presumptive US presidential nominee Donald Trump failed in their effort to hold a roll-call vote in opposition to his candidacy.

FROMELLES - Bomb sniffer dogs will be deployed and airport-style security checks will be in place for a commemorative service at Fromelles in northern France to mark the centenary of the worst day in Australian military history.

NICE - Crowds have jeered France's leaders at a tribute to victims of last week's truck attack in Nice and an opinion poll shows a sharp drop in confidence in the ability of President Francois Hollande's government to combat terrorism.

BERLIN - WikiLeaks says it is preparing to release more than 100,000 documents related to the Turkish government in the wake of a failed coup in the country that left hundreds dead, thousands injured and more than 7000 in custody.