The Global Forum for Asset Recovery will bring together governments and law enforcement agencies to discuss returning assets to Nigeria, Ukraine, Sri Lanka and Tunisia.
Foreign firms that own property in the UK must also declare their assets publicly in a bid to stamp out money-laundering, the government says.
Mr Cameron’s plans for a register of foreign companies owning UK property would include those who already owned property in the UK as well as those seeking to buy.
Downing Street said the register would mean “corrupt individuals and countries will no longer be able to move, launder and hide illicit funds through London’s property market, and will not benefit from our public funds”.
It said foreign companies owned about 100,000 properties in England and Wales and that more than 44,000 of these were in London.
David Cameron said cracking down on corruption was needed to “tackle extremism,” adding that people in developing countries wanted justice as much as they wanted clean water and health care. John Kerry, US secretary of State, agreed that corruption fed drug and human trafficking as well as terrorism.