LONDON — British Prime Minister David Cameron announced plans on Thursday to stop the flow of dirty money through the London property market, as he prepared to welcome world leaders and NGOs to an anti-corruption summit.

The foreign firms that own more than 100,000 titles in Britain, many of them anonymous offshore companies, will have to reveal their true owners, as will any foreign firms buying new property or bidding for government contracts.

The measures, intended to combat money laundering, were announced as Cameron seeks to build on public anger over the leaked Panama Papers to secure a new global commitment to tackle corruption at the summit.

The presidents of Nigeria, Afghanistan, Colombia, Ghana, Norway and Sri Lanka, US Secretary of State John Kerry and the heads of the World Bank and IMF are among those attending.

Cameron’s efforts were hampered by a gaffe in which he was caught on camera bragging that the leaders of some "fantastically corrupt" countries were attending the summit, naming Nigeria and Afghanistan.

Nigerian President Muhammadu Buhari, who has embarked on a widespread anti-corruption campaign since taking office last year, responded with a pointed request that Britain return assets stolen by corrupt officials who fled to London.

Cameron later paid tribute to the efforts of both Buhari and Afghanistan’s Ashraf Ghani in tackling corruption, and in a statement acknowledged: "The evil of corruption reaches into every corner of the world.

"A global problem needs a truly global solution. It needs an unprecedented, courageous commitment from world leaders to stand united, to speak into the silence, and to demand change."

There were reports however that the final declaration was being watered down following opposition from some countries.

It was also unclear exactly who would be signing up, with officials only confirming a handful of the 50 nations said to be attending the summit. — AFP