French Prime Minister Manuel Valls said yesterday the threat of militant attacks in the country remained “particularly high” and that exceptional security measures would stay in place as long as needed after attacks in Copenhagen.

France has deployed some 10,000 military personnel to protect public sites and announced thousands of new hires in intelligence after 17 people were killed in a series of attacks by Islamist gunmen in January.

Valls said two attacks at the weekend in Copenhagen, which targeted a synagogue and a free-speech event involving an artist who had caricatured Mohammad, underscored the need for prolonged action against what he called “Islamo-fascism”.

“We will prolong these measures as long as necessary, as long as the threat remains so high,” Valls told RTL radio, describing a security plan involving deployment of troops and police in public places and near sensitive sites.

Separately, a French prosecutor said five adolescents were arrested in conjunction with the desecration of 250 tombs in a Jewish cemetery near the northeastern city of Strasbourg on Thursday. An inquiry was opened on Sunday.

Prosecutor Philippe Vannier said the reasons for the crime were unknown, but that one of the youths denied anti-Semitism, saying they only realized they were Jewish tombs while vandalising them.

“They considered the cemetery totally abandoned,” Vannier told a press conference, adding that the vandalism involved pushing over steles and pillars and opening family vaults.

Valls called upon French Jews to remain in France and promised the “strongest possible” legal response after Israeli Prime Minister Benjamin Netanyahu called anew upon European Jews to emigrate to Israel after the Copenhagen attacks.

“My message to French Jews is as follows: France is as hurt as you are and France does not want you to leave,” he said.