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.
Copies of French newspaper Charlie Hebdo are in short supply after seven million were sold following the deaths of 10 of its journalists.
The front cover shows a cartoon of the Prophet Mohammed holding a Je Suis Charlie placard which has become a symbol for freedom of speech.
All copies sold out in France within minutes and some distributors in the UK have been unable to get copies due to such high demand.
The newspaper usually has a circulation of 60,000.
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.