The cost of corruption in Afghanistan has spiralled, with 50 percent of Afghans admitting they have bribed public officials in return for favors and services.

According to a new UN report, Afghans paid nearly $4 billion in bribes in the last year, a rise of 40 percent compared to 2009. That’s twice as much as the country’s total tax revenue.

The BBC’s Bilal Sarwary says Afghan president Hamid Karzai has pointed the finger at foreign contractors, but admits that corruption is a major problem within the government.