PARIS — Former foes France and Germany held a joint World War I Armistice Day ceremony for the first time as events around the globe Wednesday honoured the millions killed in the conflict.

President Barack Obama, speaking at a ceremony in the United States, hailed "the brave men and women of this young nation, generations of them, who above all else believed in and fought for a set of ideals."

In London, Queen Elizabeth II led tributes to the war dead, including the growing number of soldiers killed in Afghanistan. But the last British veteran of the 1914-18 conflict boycotted official events.

President Nicolas Sarkozy and Chancellor Angela Merkel rekindled the flame on the Tomb of the Unknown Soldier at the Arc de Triomphe in Paris and vowed that their nations would never wage war on each other again.

"We are not commemorating the victory of one people over another but an ordeal that was equally terrible for each side," Sarkozy declared before a military honour guard and crowds of on-lookers.

German leaders have attended World War I memorial events in France before, most notably in 1984 when Chancellor Helmut Kohl took President Francois Mitterrand's hand near Verdun, the scene of one of the war's fiercest battles.

But Merkel's visit was the first time a German leader had attended the Armistice Day ceremony in Paris and was seen as a signal of ever closer ties between the two neighbours.

The two leaders observed a moment of silence -- at the 11th hour of the 11th day of the 11th month -- to mark the moment 91 years ago when the guns stopped firing across Europe after Germany signed a treaty conceding defeat.

The Great War set the tone for the 20th century's litany of brutality and in terms of sheer mass battlefield killing has rarely been equalled.

Much of the fighting -- which pitted Germany, Austria-Hungary and Turkey against France, Britain, Russia, Italy, Australia and, from 1917, the United States -- was in northern France and was characterised by horrific trench warfare.

In Britain too, people fell silent Wednesday to remember those who fought and gave their lives in the war.

The Queen led commemorations at a service at Westminster Abbey in London which was also attended by Prime Minister Gordon Brown.

Brown has faced severe criticism this week over the war in Afghanistan, where a new generation of British service personnel are making the ultimate sacrifice.

In Camp Bastion, the main British base in Helmand province in Afghanistan, a gun salute marked the start of a two-minute silence and people stood still to pay their respects, the BBC reported.

Of the eight million British soldiers who fought in WWI, only 108-year-old Royal Navy veteran Claude Choules, who lives in Perth, Australia, remains alive. But he stayed away from official events in his adopted land.

"After my father left the navy, he never went to ANZAC Day again," Edinger told Fairfax media, referring to the day Australians and New Zealanders remember their war dead. "He didn't think we should glorify war."

The last three veterans of World War I living in Britain died this year. The last American veteran is Frank Buckles, 108, while Canadian John Babcock also survives.

The last French veteran, an Italian immigrant who lied about his age to join the Foreign Legion and fight in the trenches, died last year aged 110.

In the United States, where November 11 is a national holiday, Veterans Day, Obama attended a traditional wreath-laying ceremony at the Tomb of the Unknowns at Arlington National Cemetery near Washington.

"We don't mark this day each year as a celebration of victory as proud of that victory as we are," the president said.

"We mark this day as a celebration of those who made victory possible."

In Belgium, which saw some of the bloodiest trench warfare, King Albert II took part in a commemoration at the Tomb of the Unknown Soldier in the capital Brussels.

In Canada, Prince Charles and his wife Camilla, the Duchess of Cornwall, attended a memorial in Ottawa with Prime Minister Stephen Harper.

Solemn services took place across Australia to remember those killed in action in the war the country joined as part of the British Empire.