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.
David Cameron has called the murders at the headquarters of French satirical newspaper Charlie Hebdo "sickening".
The Prime Minister vowed to "stand with the French people" and "defend the freedom of the press".
Deputy Prime Minister Nick Clegg also took to twitter to offer his thoughts to those affected by the "barbaric attack".
While Foreign Secretary Philip Hammond said he was "appalled" to hear the news of "an apparent terrorist attack" in Paris.
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.