Anonymous activists have been spraying political graffiti across Nairobi in an underground campaign denouncing Kenya's politicians, ahead of next year's elections.

Many Kenyans have been shocked by the murals, which depict the country's politicians as vultures who exploit their position to enrich themselves whatever the cost to others.

Disputes over the last elections in 2007 degenerated into ethnic clashes which saw some 1,500 people killed and 300,000 forced from their homes. Six prominent Kenyans, including deputy Prime Minister Uhuru Kenyatta, now face charges at the International Criminal Court.

Those behind the murals say they are trying to raise awareness ahead of next year's elections and prevent a repeat.

They say it is a kind of civic education aimed at educating the youth. "Pictures stand for a thousand words," one of the artists told the BBC World Service.

"I think it's about time people said what's on their minds," said one woman. "We are saying this is what you have done and we want you to be accountable for it." The murals refer to several huge corruption scandals in which millions of dollars of public money has allegedly been stolen by corrupt politicians.

The activists have a long list of complaints... and also suggestions for what they would like from their leaders.

The only organiser willing to be named is Boniface Mwangi, an award-winning photojournalist. "We are talking about the history of this country - the biggest scandals - and the future we want," he says.

He is happy to show his face, but the street artists involved want to stay anonymous, because the murals are illegal.

Many have been painted over by local authorities who denounce the works as disrespectful and vandalism.

The artists are all volunteers - they work quickly and in the dead of night.

The vulture symbol is a favourite and appears on zebra crossings across the city