More than half of respondents in a global corruption survey released Tuesday think that graft has worsened over the past two years, and a quarter reported having paid officials a bribe in the last 12 months.

The survey by Berlin-based non-profit group Transparency International also found that people have least trust in institutions meant to help or protect them, including police, the courts and political parties.

Respondents also believed official anti-corruption efforts had deteriorated since the 2008 start of the world financial and economic crisis.

The group's Global Corruption Barometer 2013 is the world's largest public opinion survey on corruption. It surveyed 114,000 people in 107 countries, the group said.

It found that 27 per cent of respondents had said they had paid a bribe to a member of a public service or institution in the past 12 months, revealing no improvement from previous surveys.

The group pointed to a link between poverty and graft. Eight of the 10 countries with the highest bribery rates are African, said a Transparency spokesman.

In 36 countries, respondents viewed police as the most corrupt, while 20 countries view the judiciary as the most graft-ridden. In 51 countries political parties were seen as the most corrupt institution.

People's appraisal of government efforts to stop corruption was worse than before the financial crisis began in 2008, falling to 22 percent now from 31 per cent then.

Still, the group said that there was a growing will to fight back, with two-thirds of those who were asked to pay a bribe saying they had refused.

"Bribe paying levels remain very high worldwide, but people believe they have the power to stop corruption and the number of those willing to combat the abuse of power, secret dealings and bribery is significant," said Huguette Labelle, chair of Transparency International.

She added that "governments need to make sure that there are strong, independent and well-resourced institutions to prevent and redress corruption. Too many people are harmed when these core institutions and basic services are undermined by the scourge of corruption."