The colours of France's national flag dominated London landmarks this evening as Britain paid tribute to the victims of the Islamist attacks in France.

Blue, white and red dominated London's National Gallery which is adjacent to Trafalgar Square and the Tower Bridge - both popular tourist destinations.

Fifty-seven people were killed in an Islamist militant attack on London's transport system in 2005.

The London light tribute took place as a huge march, attended by dozens of world leaders and hundreds of thousands of French citizens, was taking place in the French capital Paris.

President Francois Hollande and leaders from Germany, Italy, Israel, Turkey, Britain and the Palestinian territories among others, moved off from the central Place de la Republique ahead of a sea of French and other flags.

The silent march - which may prove the largest seen in modern times through Paris - reflected shock over the worst militant Islamist assault on a European city in nine years.

For France, it raised questions of free speech, religion and security, and beyond French frontiers it exposed the vulnerability of states to urban attacks.

Seventeen people, including journalists and police, were killed in three days of violence that began on Wednesday (January 7) with a shooting attack on the weekly Charlie Hebdo known for its satirical attacks on Islam and other religions as well as politicians.

It ended on Friday with a hostage-taking at a Jewish deli in which four hostages and the gunman were killed.