Christian social justice campaigners are calling upon G20 leaders to take action to restore integrity to public life and eradicate corruption.
The EXPOSED campaign warns that corruption is depriving developing nations of $850bn a year through illicit financial flows and another $160bn as a result of tax evasion - money that could go to the provision of vital basic services, like healthcare.
The campaigners are demanding urgent action on corruption and tax evasion when G20 leaders hold a summit in November.
The call was made in an open letter organised by the EXPOSED campaign group and delivered to finance ministers meeting in Australia ahead of the summit.
The letter was signed by more than 75 church leaders and is part of EXPOSED's ongoing campaign challenging governments and corporations to greater transparency in tax and funding so that developing countries can receive what they are due.
Rev Joel Edwards, who heads up the campaign, said Christians were taking a stand against "greed, secret deals and abuse of public influence".
"We know corruption is everywhere – from football deals to corporate boardrooms. We want more integrity in public life – it makes economic sense and moral sense."
EXPOSED is looking to Australia - as the country holding the G20 presidency this year - to make sure anti-corruption measures are high on the agenda at the November summit.
"If we fail to take this opportunity we are letting down the poor," Edwards added.