A 12-year-old is among 14 French nationals missing after Hamas launched deadly raids into Israel, according to France's foreign ministry, which called the situation "worrying". Meanwhile, thousands turned out in Paris on Monday night in a show of support for Israel.
Four French people were killed in "Hamas's terrorist attacks against Israel", the French government said on their website on Tuesday.
Dozens of foreigners were killed, injured or taken hostage during a surprise attack on Israel by the Palestinian militant group Hamas Saturday that has left 800 people dead, mostly Israelis.
Many of the missing foreigners were at an electronic music festival in the southern Israeli desert, at which scores of revellers were massacred.
"Based on the information we have, we consider it highly likely that some of them have been abducted", the French foreign ministry said in a statement, adding that "this number is still subject to change".
The ministry said Monday that almost 62,000 French nationals are registered with the consulate-general in Tel Aviv, with a further 25,000 in Jerusalem.
Many French travellers were also present in Israel at the time of the attacks, it added.
The French anti-terrorist prosecutor's office, which has jurisdiction over war crimes and crimes against humanity committed against French citizens abroad, said on Monday that it was "in contact with the (French) foreign ministry".
"(This) is to obtain information on the victims and the circumstances of their deaths in order to decide whether or not to open one or more investigations," it added.
French nationals should "follow the recommendations to remain extremely vigilant issued by our teams at the French embassy in Tel Aviv, the consulate-general in Jerusalem and the Israeli authorities," the ministry urged.
Solidarity
Thousands of people, including political figures turned out for rallies in the streets of Paris and other cities on Monday evening to express their support for Israel.
Banners carried slogans such as: "Terrorism, here, there, same fight, support for Israel".
Further away, others held up a sign "Solidarity with Israel against terrorism" and the slogan "Free the hostages" was one of the most repeated.
In the evening, the Eiffel Tower and the National Assembly were illuminated in the colors of the Israeli flag.
In response to the attack, Israel is carrying out a massive air and artillery bombardment of Hamas targets in the Gaza Strip that has so far killed at least 687 people in the coastal enclave.
Hundreds of pro-Palestinian demonstrators gathered in New York on Monday to denounce the Israeli government and demand that the United States stop its support, while supporters of Israel convened for their own counter-protests and prayers.
Australian political leaders on Tuesday condemned pro-Palestinian protesters who rallied at Sydney's Opera House, some throwing flares and chanting anti-Israel insults.
World reactions
Meanwhile, from Hamburg where they had been meeting for talks, German Chancellor Olaf Scholz and France's President Emmanuel Macron vowed to stand by Israel's side.
The leaders said they planned to hold talks with US President Joe Biden and British Prime Minister Rishi Sunak.
"The United States, Britain, France and Germany are united," Scholz said.
This "must not be allowed to become a conflagration in the region... no one should fuel terror further in this situation," he said.
The leaders of the United States, France, Germany, Italy and Britain pledged in a joint statement Monday to "support Israel in its efforts to defend itself".
They added that they "recognize the legitimate aspirations of the Palestinian people" but said Hamas "offers nothing for the Palestinian people other than more terror and bloodshed," in the statement released by the White House.
(with newswires)
