War-torn nations remain the world's most corrupt, Transparency International (TI) has said.
Afghanistan, Iraq and Somalia are the lowest-ranked countries in TI's annual global survey. They were all at the bottom of the list last year as well.
"When essential institutions are weak or non-existent, corruption spirals out of control," TI said.
New Zealand was the least corrupt, with last year's winner Denmark as runner-up and Singapore third.
It said this was a result of "political stability, long established conflict of interest regulations and solid, functioning public institutions". 
The issue of corruption in Afghanistan is particularly pressing. Widespread fraud marred the country's last elections, while the US is still debating whether to increase troop levels.
The UK ranked 17th, down one place from last year. The US also fell one place to 19th.
The organisation said tackling public sector corruption was even more pressing now, as governments worldwide had spent huge amounts of public money bailing out banks and public institutions.
"At a time when massive stimulus packages, fast-track disbursements of public funds and attempts to secure peace are being implemented around the world, it is essential to identify where corruption blocks good governance and accountability," TI said.
TI also welcomed action by the OECD and G20 group of richest 
nations to tackle tax havens and other places where corrupt government officials often harbour their money.
"Corrupt money must not find a safe haven," it said. "The OECD's work in this area is welcome, but there must be more bilateral treaties on information exchange to fully end the secrecy regime."
