Paris is on high alert as world leaders converge on the city for a march expected to draw millions of people in a demonstration of national unity.

French Prime Minister Manuel Valls predicted the huge turnout to honour the 17 people killed in attacks on the satirical magazine Charlie Hebdo, a kosher supermarket and the police.

With the country's national security threat system still at the highest level and a suspected member of the terror cell behind the attacks on the run, France has deployed thousands of police and troops to protect the capital.

More than 5,500 police and military personnel will be deployed, including 2,200 to guard the route of the march, which will run for 3kms from the historic Place de la Republique to Place de la Nation.

Among those there is the Taoiseach Enda Kenny - who has released a statement, explaining his reasons for being there:

Today we march to show that Liberte, Egalite, Fraternity are written, not alone on the history and monuments of the Fifth Republic but in the hearts and minds of the people of France and our European Union.

Voltaire wrote that 'tolerance is the consequence of our humanity'.

And today we march here in his city to defend that tolerance and humanity against the hatred and extremism that would dismantle and destroy them.

In our solidarity we show the agents of such destruction that to us their actions are anathema, their propositions absurd.

The city of Paris has known revolution, occupation terror, old and new.

Yet today in defiance of history old enemies march here to defend the values of respect, freedom, dignity and tolerance.

Values, this week so-well recited by the living so-well practised by the dead that even in the depth of darkness they confirm the city of Paris as the City of Light.

And today as we march through its streets or join in on screens across the world we are, all of us, its citizens we keep and live in its light.

Je Suis Charlie, nous sommes tous Parisiens.

Today, I say to President Hollande and his government and to the people of France and of our Union - may our presence and witness here deepen our sense of brotherhood and sisterhood.

Together, as Europeans, may we nourish our democracy, protect our liberty, cherish our way of life.

And in the face of terror may our humanity sustain us and renew us. May it be as shattering as our sadness and our silence on this January day.