PARIS (AP) – France’s prime minister lamented the growing number of departures of French Jews for Israel, as he and Jewish leaders honored four people gunned down in a kosher market a year ago by an attacker claiming ties to the Islamic State group.

Saturday evening’s ceremony was part of a weekend of efforts to ease religious tensions and mark the anniversary of the attacks on the market and the satirical newspaper Charlie Hebdo. Times remain tense for France’s large Jewish and Muslim communities after a year marked by Islamic extremist violence that left more than 150 people dead.

Mosques all over France are opening up to the public this weekend to ease anti-Muslim sentiment and highlight the differences between jihadism and moderate Islam.

Prime Minister Manuel Valls joined families of victims and survivors to mark the anniversary of the Jan. 9, 2015 shooting and hostage-taking at the Hypercacher market in eastern Paris, which ended with attacker Amedy Coulibaly slain by police.

“France would not be France” without its Jews, Valls said. He called it intolerable “to see French Jews leave their country, in larger and larger numbers, because they no longer feel safe” or at home.

“For these enemies who attack their compatriots, who tear apart the contract that unites us, there can be no worthy explanation,” he said, acknowledging the “immense anguish” of the Jewish community.

More French Jews emigrated to Israel last year than ever before, according to figures from the Jewish Agency — some because of security concerns after last year’s market siege.

Concerns about anti-Semitism in France had already been high, and 2014 also saw a record number of French Jews emigrate to Israel.

The mood was somber at Saturday’s ceremony, as members of the French Jewish community urged government efforts against extremism.

“These kinds of events are happening again and again and again,” said Parisian Rachel Benecmous. “Every time we are weakened when these events are repeated, so it’s difficult. We are weakened and traumatized, but … we organize ourselves so that terrorism will not win and affect our morale.”

France’s main Muslim body organized a mosque open-door initiative this weekend, including tea and pastries, to reduce tensions. Attacks on Nov. 13 in Paris led police to conduct over a dozen raids on Muslim places of worship and close several over fears they were radicalizing members.

French President Francois Hollande paid homage Saturday to a female police officer, Clarissa Jean-Philippe, who was killed by Coulibaly in the Parisian suburb of Montrouge on Jan. 8.

Hollande unveiled a memorial plaque and stood solemnly amid a rousing rendition of the Marseillaise, followed by spontaneous gospel music.

“I am not bitter,” said the victim’s mother, Marie-Louise Jean-Philippe. She told French media that the “beautiful ceremony” warmed her heart.