World leaders, NGOs and financial institutions gather in London on Thursday for an anti-corruption summit that host Prime Minister David Cameron has said will spur new global action in the wake of the Panama Papers leaks.
About 40 countries have been invited alongside bodies such as the World Bank and the IMF, with the presidents of Afghanistan, Colombia and Nigeria and US Secretary of State John Kerry among those due to attend.
"Corruption is an enemy of progress and the root of so many of the world's problems," Cameron said.
Campaigners are hoping for concrete action in response to public outrage over the revelations in the so-called Panama Papers of how the rich and powerful hide their money.
They want governments to expose the beneficiaries of anonymous companies used to move money without detection, and take further action to reduce the secrecy of offshore tax havens where they are incorporated.
There is also speculation that Cameron will announce measures to tackle money laundering through London's luxury property market, following his declaration last year that there was "no place for dirty money in Britain".
A Downing Street spokesman said the summit declaration would commit signatories "to expose corruption wherever it is found, to pursue and punish those who perpetrate, facilitate or are complicit in it".
It will also promise to support victims and ensure corruption "does not fester" in government, business or communities, the spokesman said.
But The Times reported that the final statement will be watered down following opposition from some countries, with one passage stating there would be "no impunity for the corrupt" removed.
The Russian foreign ministry, which is sending deputy foreign minister Oleg Syromolotov, has already indicated that any final agreement may not be binding.
Robert Barrington, UK executive director of advocacy group Transparency International, said Cameron should "not give in" to attempts to limit the summit's ambitions.
"The prime minister has created a platform for governments that are serious about fighting corruption, and now it is up to others to show they share the same ambition," he said.
- 'Clean out your own backyard' -
Cameron has led international calls to tackle aggressive tax avoidance and evasion and global corruption, but was embarrassed last month when his late father's Bahamas-based investment fund was revealed in the Panama leaks.
The release of 11.5 million confidential documents from Panamanian law firm Mossack Fonseca also shone a spotlight on the secrecy of Britain's overseas tax havens.
More than 113,000 out of the 210,000 companies exposed were registered in the British Virgin Islands.
Britain will introduce a public register on who ultimately benefits from British-registered companies -- so-called beneficial ownership -- next month, the first G20 and EU nation to do so.
But campaigners want London to extend the measure to its overseas territories, forcing them if necessary.
"If you're going to stake out a claim to be a leader, clean out your own backyard," said John Christensen of the Tax Justice Network advocacy group.
More than 300 economists, including former IMF economist Oliver Blanchard and France's Thomas Piketty, urged world leaders to end offshore financial secrecy, saying tax havens "serve no useful economic purpose".
Kerry is also under pressure to address the lack of transparency in US states such as Delaware and Wyoming, where anonymous companies can be created for just a few hundred dollars.
- Shady property deals -
The Panama leaks also highlighted how global elites used offshore companies to buy expensive London property, fuelling concerns of money-laundering through the capital.
More than £180 million ($260 million, 228 million euros) of property in Britain was investigated as suspected proceeds of corruption between 2004 and 2014, according to Transparency International, which says this figure is just the "tip of the iceberg".
Reports suggest the government may announce plans to force foreign companies that buy property to reveal their owners, although it is not clear if this would apply to the existing 100,000 titles registered to overseas firms.
"If properly implemented, this would be a big problem for anyone wanting to launder money here," said Eleanor Nichol of advocacy group Global Witness.
In an open letter to Cameron ahead of the summit, almost 100 Nigerian civil society groups warned Britain was a "safe haven for our corrupt individuals".
"This summit is an opportunity for the major financial centres to finally acknowledge the role they are playing in perpetuating corruption," they wrote.