Paris, Jan 8 (IANS): The deadly attack on a French satirical magazine office Wednesday is a tragic reminder that the freedom of expression is fragile and those who defend it may pay the ultimate price for doing so, Unesco Director-General Irina Bokova said Thursday.

Hooded gunmen dressed in black burst into the office of French satirical magazine Charlie Hebdo Wednesday, killing 12 people in a coordinated strike with automatic weapons.

This attack was condemned worldwide by various agencies, who said it was an "assault on the universal right of freedom".

"Never before has one media outlet been so deliberately targeted and its staff decimated in an act of such extreme violence," Bokova said, condemning the attack.

"This cowardly attack stands condemned by the entire world. Those responsible must be brought to justice and punished. But beyond that, governments and civil society must remain firm before such aggression, and refuse any attempt to undermine the hard-fought values that people everywhere hold so dear," she added.

The assailants killed 12 people -- including Charlie Hebdo's editor and three acclaimed cartoonists -- and left 11 others wounded.

After the incident, peaceful candlelight vigils were staged throughout France, and Bokova pointed how these demonstrations have reinforced how freedom of expression is cherished worldwide.

"The spontaneous demonstrations that this appalling crime has provoked across France and around the world -- the outpouring of sorrow and anger expressed by citizens from all faiths -- also reveal that freedom of expression is a right that is cherished, and understood by all as being at the heart of healthy, functioning societies," she said.

"Charlie Hebdo championed this right fiercely, often drawing sharp criticism, threats and other attacks. But its journalists and cartoonists bravely held their ground, passionate in their conviction that freedom of expression must be defended against all odds," she added.