Anti-corruption experts from around the world have gathered in London to promote international co-operation in the hunt for assets believed to run into billions of pounds stolen from Ukraine by ousted president Viktor Yanukovych and his regime.
Home Secretary Theresa May, co-hosting the Ukraine Forum on Asset Recovery at Lancaster House with US attorney general Eric Holder, said that the meeting was a "tangible manifestation" of determination not to allow impunity to leaders who loot the assets of their own countries.
The forum came as new sanctions imposed by the European Union came into force, as the West responded to continued unrest in the east of Ukraine.
The EU has released the names of 15 new targets for sanctions because of their roles in the Ukraine crisis, including chief of the Russian general staff Valery Gerasimov, head of the military intelligence agency Igor Sergun, Russian deputy prime minister Dmitry Kozak and pro-Russian separatist leaders in Crimea and the eastern Ukrainian cities of Lugansk and Donetsk.
The EU list does not match sanctions imposed by the US, which also include actions against businesses such as the Russian energy giant Rosneft, but Mr Holder said he was "satisfied" with Europe's response.
Asked whether the White House was considering targeting the personal assets of Russian president Vladimir Putin himself, Mr Holder said: "We believe that Russia must cease its illegal intervention and its provocative actions in Ukraine and we remain prepared to impose further sanctions if that doesn't occur."
Ukraine's general prosecutor Oleh Makhnitskyi told the London forum that the country has already identified stolen assets totalling at least 35 billion Ukrainian hryvnias (£1.8 billion) and expects the eventual total to amount to tens of billions of US dollars. Funds are believed to have been transferred to international bank accounts in countries around the world.
Describing the Yanukovych regime as an "organised criminal group" whose tentacles reached throughout the administration, Mr Makhnitskyi said; "The new government was set up and we found that our treasury was empty and the funds were misappropriated."
Mr Holder said the US was determined to track down and repatriate assets stolen by the Yanukovych regime, but acknowledged that it would be a slow and lengthy process which could take a number of years to produce results.
"There should be no mistake," he told a press conference. "We are determined in our efforts to be successful. We are determined to hold accountable those who were responsible for the theft of these Ukrainian assets and we are also determined to ensure that those assets are returned to the Ukrainian people to be used in an appropriate way."
In a message to countries accused of dragging their feet over the identification and repatriation of assets, Mr Holder said: "Decisions have to be made. What side are you on?
"Do you stand with the Ukrainian people or do you stand with those who have robbed and stolen from the Ukrainian people? It's a simple decision."
Mr Holder announced the creation of a Kleptocracy Squad within the FBI tasked with "aggressively investigating and prosecuting corruption cases not only in Ukraine, but around the world".
Mrs May said officials from Britain's National Crime Agency and Crown Prosecution Service have already travelled to Ukraine to offer their assistance.
Speaking at the opening of the two-day forum, the Home Secretary said: "I think this event will help to set a new benchmark for the international community by demonstrating our shared determination to prevent our open societies and open economies from being used by corrupt individuals to launder and hide stolen funds."