The best way to honour those killed in the attack on French magazine Charlie Hebdo's Paris office would be to campaign for freedom of expression around the world, the Cape Town Press Club said on Thursday.

"The brazen attack on the offices of French magazine Charlie Hebdo has very correctly been condemned far and wide," the club said in a statement.

"By the latest count, 12 people lost their lives for expressing or defending the freedom that so many of us across the world take for granted."

The Associated Press reported on Thursday that French police were hunting for two heavily armed men, one with possible links to Al-Qaeda, for the methodical killing of 12 people at the satirical newspaper that published caricatures of the Prophet Mohammed. The attack took place on Wednesday.

France began a day of national mourning for what its president called "an act of exceptional barbarism", AP reported.

The press club said the death of free speech was a loss to all.

"No matter where you live, you should have the inalienable right to express yourself freely and not to fear a physical or violent act of reprisal in response," it said.

"The Cape Town Press Club hopes that the perpetrators of this abhorrent act will be made [to face] the full might of the law as soon as is possible."