A leading figure in the fight against a hugely unpopular Colombian mining project has been shot dead in front of his wife and son.

Human rights groups have reported that Cesar Garcia was shot in the head on November 2 when he returned to his farm with his family at dusk.

More than 800 people attended his funeral on Monday, filling the church to overflowing despite heavy rain.

Mr Garcia was president of his local neighbourhood association and a member of the Peasant and Environmental Committee of Cajamarca - part of a regional network opposed to the huge proposed Anglo-Gold Ashanti mining project.

The mooted La Colosa goldmine would be the largest in Colombia and seventh-largest in the world.

Right-wing President Juan Manuel Santos has been trying to force through the project despite mass opposition.

Locals overwhelmingly rejected the environmentally ruinous mine in a region referendum in July, with 98.8 per cent voting against it on a 60 per cent turnout.

But Ashanti bosses have branded opponents of the project "guerillas" while police have repressed protests and leaders of the movement have received death threats.

When a group surveying the land around the mine were attacked with two bombs thrown from the mountain, local media immediately blamed environmentalists.

British-based Justice for Colombia said the assassination was "further evidence of the stigmatisation and repression of Colombia's peasant and environmentalist movement."

A Colombia Solidarity Campaign protest will be held at 4pm today outside the Colombian embassy, 3 Hans Crescent, London SW1X