PARIS (AFP) - Thousands marched in Western capitals on Saturday to support the people of Syria, who entered the fourth year of a conflict that has left at least 146,000 dead and spawned the world's largest displaced population.

Around 1,000 people marched to Downing Street in London, waving Syrian flags and denouncing the international community's inaction.

"Gassed to death, starved to death, frozen to death... You watched", "Your silence is killing us", "Revolution until victory, Syrians deserve life", read some of the banners.

A famous stencil by graffiti artist Banksy, reworked to depict a Syrian refugee girl with a heart-shaped balloon, was projected on Nelson's Column in Trafalgar Square.

Most of the demonstrators were Syrians, as was the case at a similar event in Rome, where 3,000 people marched through the city centre to protest against the regime of President Bashar al-Assad.

Hundreds also showed up in Madrid and in Paris, where messages of support to Syria were lit up on the Eiffel Tower.

"We are here today, three years after the start of the repression and the conflict, to support the Syrians who are there and in our country," the head of the French branch of Amnesty International, Ms Genevieve Garrigos, told Agence France-Presse.

In Washington, around 1,000 people chanted "revolution" and other slogans against Assad. They gathered in front of the White House and read out the names of some of the conflict's victims.