The poor are hit hardest by corruption

The report added that the world's poor were the hardest hit by bribery.

The police and judiciary were the worst offenders, with one quarter of those who come into contact with the police paying a bribe.

About half believe corruption is on the rise and 70% said political parties were the most corrupt institutions.

"The police and the judiciary in many countries around the world are part of a cycle of corruption, demanding bribes from citizens," said Transparency International managing director Cobus de Swardt.

WHO PAYS THE MOST BRIBES Cameroon - 79% Cambodia - 72% Albania - 71% Kosovo - 67% FYR Macedonia - 44% Pakistan - 44% Nigeria - 40% Senegal - 38% Romania - 33% Philippines - 32% Percentage of people who paid a bribe in the past 12 months (Source: Transparency International)

While the police may get the worst criticism on a global basis, within Europe people are most likely to pay bribes for medical services.

Tax on poor

The popular perception may be that bribes are paid by wealthy people to gain influence and oil the wheels of power, but they are mostly paid by poor people to ensure they get basic public services.

"Extortion hits low-income households with a regressive tax that saps scarce household resources," the report said

Corruption levels vary across the globe.

In Africa, 42% of people paid a bribe to obtain a service, though this figure is down from 47% in 2006.

WHO PAYS THE FEWEST BRIBES Austria - 1% Canada - 1% France - 1% Iceland - 1% Japan - 1% South Korea - 1% Sweden - 1% Switzerland - 1% Denmark - 2% Netherlands - 2% Percentage of people who paid a bribe in the past 12 months (Source: Transparency International)

Elsewhere, petty bribery was on the rise, with 22% of people in the Asia Pacific region paying a bribe in 2007, up from 15% in 2006. In south-east Europe, 12% paid a bribe, up from 8%.

While Africa is the region most affected by bribery, Africans, particularly Ghanaians and Nigerians, were optimistic about their government's anti-corruption efforts.

But half of those interviewed globally think their government's efforts to fight corruption are ineffective.

The institutions which fared best were religious bodies and non-governmental organisations (NGOs) - though the perception of NGOs has worsened since the last survey.

Transparency International's Global Corruption Barometer 2007 interviewed 63,199 people in 60 countries and territories between June and September 2007.