LONDON/VIENNA (Reuters/AFP) - Corruption costs Afghans $2.5 billion a year, a United Nations agency said on Tuesday, with the scale of bribery matching Afghanistans opium trade. Corruption is the biggest worry for Afghans, more so than insecurity or unemployment, according to the findings of a new UN report. In a report entitled Corruption in Afghanistan, the United Nations Office on Drugs and Crime (UNODC) found that 59 per cent of the Afghan population felt that public dishonesty is a bigger concern than insecurity (with 54 per cent) or unemployment (52 per cent). Bribery is a crippling tax on people who are already among the worlds poorest, UNODCs Executive Director Antonio Maria Costa said in a statement, adding the scale of corruption was equivalent to nearly a quarter of the countrys economic output. The cancer of corruption in Afghanistan is metastatic, Costa warned. He urged Afghan President Hamid Karzai to urgently administer tough medicine based on the United Nations Convention against Corruption which he pushed so hard to ratify. More than half - 54 per cent - of Afghans believed that international organisations and NGOs (non-governmental organisations) are corrupt and are in the country just to get rich, the report said. Karzai, when he was sworn in for a second five-year term in November after a tainted election, promised measures to fight graft. But he has also defended his record on corruption, saying the issue had been blown out of proportion by Western media. The report, based on interviews with 7,600 Afghans conducted between August and October last year with people in 12 provincial capitals and more than 1,600 villages around Afghanistan, found that graft was part of everyday life. In the past year, one Afghan out of two had to pay at least one kickback to a public official such as a police officer, judge, prosecutor or member of the government. More than half of the time (56 per cent), the request for illicit payment was an explicit demand by the service provider, it said. The average bribe was $160 in a country where economic output per capita is just $425 a year. In total, Afghans paid out $2.5 billion in bribes over the previous 12 months, equivalent to 23 per cent of Afghanistans Gross Domestic Product and similar to the proceeds of Afghanistans opium trade, the report said. This was similar to the revenue of the opium trade in Afghanistan in 2009, which UNODC estimated at $2.8 billion. Citizens were asked for bribes when they needed a document or a license, to have their rights protected in courts or to receive medical treatment, the report said. The biggest culprits were police and local officials, followed by judges, prosecutors, or members of the government, the UNODC found. Costa urged Karzai to turn the High Office of Oversight and Anti-Corruption into an independent, fearless and well funded anti-corruption authority. At the moment, this is not the case. Public officials should be vigorously vetted, including through the use of lie detectors; public servants should disclose their incomes and assets; and governors and local administrators with proven records of collusion with shady characters should be removed, he said. He called for transparency in public procurement, tenders and political campaigns, and for tighter regulation of financial institutions to prevent money laundering.