One in four people paid a bribe in dealing with public services and institutions in the past 12 months, according to a global corruption survey.

In the world's largest assessment of public opinion on the subject, Transparency International found that political parties are considered the most corrupt institutions, followed by the police, the judiciary, parliament and public officials. Religious institutions are seen as the least corrupt.

Transparency International says its annual survey shows a crisis of trust in politics and real concern about the capacity of institutions responsible for bringing criminals to justice.

"It is the actors that are supposed to be running countries and upholding the rule of law that are seen as the most corrupt, judged to be abusing their positions of power and acting in their own interests rather than for citizens they are there to represent and serve," said the global corruption barometer, a survey of 114,000 people in 107 countries.

Politicians could lead by example by publishing asset declarations for themselves and their immediate family, suggested Transparency International. Political parties and individual candidates should disclose where they get their money from to make clear who funds them and reveal potential conflicts of interest.

According to the survey, many people regard corruption as a very serious problem for their societies. On a scale of one to five, where one means "corruption is not a problem at all" and five means "corruption is a very serious problem", the average score across the countries surveyed was 4.1. Concern was highest in Liberia and Mongolia, which both scored 4.8. More optimistic were people in Denmark, Finland, Rwanda, Sudan and Switzerland, all of which recorded scores below three.

Of the 107 countries surveyed, only 11, including Azerbaijan, Rwanda and South Sudan, thought corruption had decreased.

The survey reported that 27% of respondents had paid a bribe – the most direct experience of corruption for a person – with police the most often bribed institution. Police bribery rates were highest in the Democratic of the Republic of the Congo (75%), Ghana, Indonesia, Kenya, Liberia, Nigeria and Sierra Leone.

Corruption in the land sector can be particularly critical. One in five people report having paid a bribe for services such as registration or land transfer. Those who cannot make illegal payments are left with little or no protection under law, making them vulnerable to eviction and abuse.

High bribery rates for land services in Afghanistan, Cambodia, Iraq, Liberia, Pakistan and Sierra Leone, which range from 39% to 75%, are an especially marked concern.

"Corruption in the land sector is particularly critical in post-conflict societies and countries in transition, where transparent and efficient land management is necessary to rebuild and reconstruct the country," said the survey.

Nearly nine out of 10 people surveyed said they would act against corruption, however, while two-thirds of those asked to pay a bribe refused. Most said they would be willing to report corruption. However, compared with the 2010-11 survey, belief in citizens' power to address corruption has dropped from 72% to 67% across the 91 countries covered by both surveys.

"Governments need to make sure that there are strong, independent and well-resourced institutions to prevent and redress corruption," said Huguette Labelle, chair of Transparency International. "Too many people are harmed when these core institutions and basic services are undermined by the scourge of corruption."

Case study

Ahmed, living in a slum with his wife and two children, was entitled to a new plot of land under a national programme in Morocco to move slum dwellers to cleaner homes. But the public officials responsible for administering the programme used their position of power to allocate land only to those people who could pay. Unable to do so, Ahmed and his family were left homeless when their slum was destroyed.