A new study of corruption in Kenya by the group Transparency International, which surveys corruptional around the world, has found that people living in cities there spend almost one third of their income on bribes.

The launch of Transparency International's first Kenya Urban Bribery Index began with a song by popular local musician Eric Wainaina, who sang "Nchi ya kitu kidogo." Kitu kidogo means "something small" in the Kiswahili language. The phrase is a familiar one to Kenyans, as it is what people usually ask for when soliciting bribes.

According to Transparency International, the police had the dubious honor of scoring highest in the bribery index; six out of 10 urban residents said they have had to bribe police to avoid being mistreated. But the survey shows that dealing with officials at just about every level of Kenyan society - from local councils to the court system to immigration officials - requires payment of kitu kidogo.

The survey says Kenyans spend a huge amount of money on bribes - over $100 a month, almost a third of their income. On average, people pay 16 bribes a month, 10 of which are to the police.

David Ndii, research adviser for Transparency International, says corruption extends to all levels of Kenyan society. Junior officials who take bribes usually pass some of the money on to more senior members of staff. As an example, Mr. Ndii said police frequently pay their superiors for assigning them to particularly lucrative routes. "There is actually a market for routes where you can collect more bribes, an internal market in the police force where people buy from their superiors particular sort of routes to operate, and you have quotas about how much you deliver [to your superior]," explained Mr. Ndii.

Corruption has long been a problem in Kenya, but until now, the emphasis has been on prosecuting the so-called big fish - senior government figures involved in the theft of public funds. But Mr. Ndii said the survey proves that day-to-day petty bribery is an even greater problem.

Neither the police spokesman, nor the police commissioner, nor the government's chief of protocol were available for comment on the survey.

Earlier this week, Kenyan President Daniel arap Moi appointed a team of international experts to advise the government how to fight corruption.