Kabul - Half of all Afghans paid a bribe to public officials in 2012 while the cost of corruption has risen to 3.9 billion dollars, according to a survey released by the United Nations on Thursday.
"The bribes that Afghan citizens paid in 2012, equals double Afghanistan's domestic revenue," said Jean-Luc Lemahieu of the UN's Office on Drugs and Crime (UNDOC), which conducted the survey with the Afghan government's corruption watchdog.
The report said that Afghanistan has made "tangible progress in reducing corruption" but its cost to the country has increased 40 per cent since 2009.
More than 6,700 people across Afghanistan were interviewed for the report titled Corruption in Afghanistan: Recent Patterns and Trends.
Lemahieu said Afghans consider corruption to be the country's "number-two most important issue after security problems."
The report said the average cost of a bribe paid by Afghans in 2012 has risen from 158 dollars to 214 dollars since 2009, a 29-per-cent increase.
The police, judicial system, local governments and the Ministry of Education were found to have widespread corruption in their administrations and provision of public services, according to the survey.
The survey found 42 per cent of Afghans had paid a bribe to police officers, a fall of 10 percentage points since 2009.
In southern Afghanistan, where insurgents are more active, the report said that local tribal elders and Taliban groups are more involved in bribery.
A spokesman for the Education Ministry rejected the allegations, calling them "untrue", "unrealistic" and politically motivated.
"The survey represents public opinion and the government of Afghanistan together with all other administrations support this survey," said Mohammad Rafi Amini, an official with the government's High Office of Oversight and Anti-Corruption.