Hundreds of people queued from the early hours outside UK shops selling the latest edition of French satirical magazine Charlie Hebdo.
It comes as around 10 people have been arrested and questioned over the "possible logistical support" they may have provided three gunmen who carried out last week's attacks in Paris, Agence France-Presse reports.
Novelist Salman Rushdie has condemned what he calls "religious totalitarianism" after the massacre at Charlie Hebdo magazine headquarters in Paris.
Rushdie - who himself was sentenced to death by Iran's rulers and was subject of a series of death threats from hardline critics of his novel The Satanic Verses - called religion a "medieval form of unreason".
"This religious totalitarianism has caused a deadly mutation in the heart of Islam and we see the tragic consequences in Paris today," he said.
About 7,000 French Jewish people left the country last year and have moved to Israel because they did not feel safe.
The aunt of a man killed while trying to overpower gunman Amedy Coulibaly has told ITV News her family is fearful of their future in France.
A Muslim cleric in Pakistan has held a ceremony to honour Cherif and Said Kouachi, the two men suspected of the Charlie Hebdo massacre.