World leaders and hundreds of thousands of French citizens are gathering in Paris ahead of a march to show solidarity and protest against three days of deadly attacks in and around the city.

More than 40 heads of state and government are expected to attend, including the Israeli prime minister Benjamin Netanyahu, King Abdullah of Jordan and Palestinian leader Mahmoud Abbas.

German chancellor Angela Merkel, British prime minister David Cameron and Italian prime minister Matteo Renzi will also march alongside French president Francois Hollande.

• ‘Live together, free, equal and in solidarity’
• Tribute to ‘pillar’ of their family
• French police hunt gunman’s girlfriend

Seventeen people, including journalists and policemen, lost their lives in three days of violence that began with a shooting attack on the satirical newspaper Charlie Hebdo on Wednesday and ended with a hostage-taking at a kosher supermarket on Friday. The three gunmen were also killed.

Close to a million people are expected to take part in the silent march through the centre of Paris, in honour of the victims of the worst terror attacks in the city for 50 years.

The huge gathering of people follows rallies in towns and cities across the country involving hundreds of thousands of people.

“It will be an unprecedented manifestation that will be written in the history books,” French prime minister Manuel Valls said.

“It must show the power and dignity of the French people, who will cry out their love of liberty and tolerance,” he said.

Across France on Saturday, hundreds of thousands of people took part in rallies to demonstrate against the attacks.

Many people carried signs saying “Je suis Charlie” (I am Charlie) in reference to the magazine where 12 people, including its top cartoonists, were killed on Wednesday.

Unprecedented security presence to monitor Paris streets

A massive security presence will be in place along the three routes the march is expected to take through the city from La Place de la Republique, including both police and soldiers.

There will be around 5,500 police officers on the streets, as well as snipers located on rooftops and helicopters monitoring from the sky.

That is in addition to the 89,000 French gendarmes who have been placed on heightened alert over the past three days after the attacks that have shocked France.

Hours before the Paris rally, German police said they were investigating whether an arson attack on the offices of a German newspaper was linked to its earlier publication of Charlie Hebdo cartoons, featuring the prophet Mohammed.

French leaders have already warned that the threat may not yet be over and are appealing for calm and for unity.

“Everything will be done to make sure that those who want to come to this meeting can do so safely,” interior minister Bernard Cazeneuve said.

Mr Hollande also said he would visit the Grand Synagogue of Paris after the march. Four Jews were killed in the attack on the supermarket.

However, right-wing National Front leader Marine Le Pen, who is expected to receive a boost in the polls due to the attacks, said her party would shun the Paris demonstration and instead take part in regional marches.

She accused the Socialist government of trying to take advantage of the event to win greater support.

French police continue hunt for attack accomplice

Turkish and French sources say a woman being hunted by French police as a suspect in the attacks had left France several days before the killings and is believed to be in Syria.

French police have launched an intensive search for Hayat Boumeddiene, the 26-year-old partner of one of the attackers, describing her as “armed and dangerous”.

A senior Turkish official said Boumeddine left France last week and travelled to Syria via Turkey, saying she passed through Istanbul on January 2.

Turkish authorities said Paris and Ankara are now cooperating in trying to trace her but that she had arrived in Istanbul without any warning from France.

“We think she is in Syria at the moment but we do not have any evidence about that,” the Turkish official said.

“She is most probably not in Turkey.”