PARIS (AFP) - World leaders, including some who are normally implacable foes, on Sunday linked arms in unprecedented scenes of solidarity during an historic march against terrorism in Paris.

Walking arm in arm alongside President Francois Hollande were a string of leaders including British Prime Minister David Cameron and German Chancellor Angela Merkel.

They were joined on the front line by arch nemeses Israeli leader Benjamin Netanyahu and Palestinian President Mahmud Abbas, who were positioned just four people apart.

Also present were Ukrainian President Petro Poroshenko and Russian Foreign Minister Sergei Lavrov, whose countries are engaged in a violent struggle in Ukraine.

"Paris is the capital of the world today," said Hollande before the march, which attracted hundreds of thousands to the streets of Paris and many more across the rest of France and Europe.

Before he set off for the march, Britain's David Cameron said: "We in Britain face a very similar threat, a threat of fanatical extremism.

"It's a threat that has been with us for many years and I believe will be with us for many more years to come," he told Sky News.

Italy's Prime Minister Matteo Renzi vowed that Europe would "win the challenge against terrorism".

The procession was organised in record time following a three-day extremist killing spree that saw 17 people - police, prominent cartoonists, shoppers and others - die at the hands of three gunmen.

The dramatic events ended Friday when the attackers took hostages in two separate locations and were eventually shot dead by security forces in simultaneous assaults.