LONDON (AFP) - Soil from World War I battlefields in Belgium was laid in a memorial garden in London on Saturday ahead of the 100th anniversary next year of the start of the conflict.

Seventy bags of "sacred soil" gathered by more than 1,000 British and Belgian schoolchildren earlier this year arrived in Britain by Belgian warship on Friday.

On Saturday, a horsedrawn army gun carriage took the bags past landmarks including Buckingham Palace and St Paul's Cathedral to the new memorial garden at Wellington barracks in central London.

The soil was blessed in a ceremony at the Guards' Chapel before eight-year-old schoolboy Patrick Casey was given the honour of pouring a crucible of soil taken from all the battlefields into the heart of the garden.

Queen Elizabeth II's husband Prince Philip, 92, was presented with the soil in a ceremony in the Belgian town of Ypres earlier this month, to remember the tens of thousands of Commonwealth soldiers who died in the 1914-18 war.

British junior defence minister John Astor, who attended the ceremony with the premier of Flanders Kris Peeters, said it was a "very moving ceremony".

"They were killed for our freedom, they paid a very high price for that, and we are enjoying the freedom now," Astor said.

Designed by Belgian architect Piet Blanckaert, the Flanders Fields 1914-2014 Memorial Garden is intended as "a symbol of hope and a better future for all", according to organisers.