World condemns Paris attack

The UN Security Council has led global condemnation of the "terrorist" shooting at French magazine Charlie Hebdo which left 12 people dead.

US President Barack Obama and the Queen on Wednesday offered their condolences to those affected after masked men armed with Kalashnikov automatic rifles opened fire at the Paris offices of the satirical weekly.

Pope Francis said there could be no justification for "the horrible attack that plunged the city of Paris into mourning".

The Committee to Protect Journalists said the shooting was a "brazen assault on free expression in the heart of Europe", while Reporters Without Borders called it a "black day".

On social media, people across the world showed their solidarity with the publication by posting the hashtag #JeSuisCharlie - "I am Charlie".

Tens of thousands also rallied in cities across France and Europe in a show of solidarity with the victims.

French President Francois Hollande condemned as a "terrorist attack" the massacre at the publication, which has been in confrontation for years with Islamists who accused it of attacking their religion through cartoons.

Hollande's characterisation of the incident was echoed by the 15-member UN Security Council, which condemned the "barbaric and cowardly terrorist attack".

UN Secretary-General Ban Ki-moon said the "horrendous, unjustifiable and cold-blooded crime" was "meant to divide. We must not fall into that trap".

Obama said: "Our thoughts and prayers are with the victims of this terrorist attack and the people of France at this difficult time."

US Secretary of State John Kerry later addressed the people of France in televised remarks in French, saying: "All Americans stand by your side."

In Rome, Italian Prime Minister Matteo Renzi went to the French embassy to say: "We are all French, because we think freedom is the only raison d'etre of Europe and European citizens."

British Prime Minister David Cameron said the attack was "sickening", while German Chancellor Angela Merkel called it "despicable", sentiments reflected across European capitals.

In a rare statement on international events, the Queen offered her "sincere condolences" to those affected by the attack.

There was also condemnation from Russian President Vladimir Putin, Canadian Prime Minister Stephen Harper, Japanese Prime Minister Shinzo Abe, Turkish President Recep Tayyip Erdogan, Egyptian President Abdel Fattah al-Sisi and the Chinese foreign ministry among others.

Israeli Prime Minister Benjamin Netanyahu for his part called for global unity to fight the "scourge" of radical Islam.

The foreign ministry of Qatar, which is accused of backing radical Islamic groups,said: "Such acts that target unarmed civilians contradict all principles and moral and human values."

Iran also condemned the massacre but reiterated its criticism of the magazine's 2006 publication of cartoons of the Prophet Mohammed.

"Making use of freedom of expression ... to humiliate the monotheistic religions and their values and symbols is unacceptable," foreign ministry spokeswoman Marzieh Afkham told the official IRNA news agency.

The gunmen were heard to shout "we have avenged the prophet" and "Allahu akbar" ("God is greatest"), according to French police.