In a rare joint statement on Tuesday, Chancellor Rachel Reeves and Foreign Secretary David Lammy expressed frustration over the lack of progress in negotiations with Abramovich, whose assets were frozen following sanctions imposed during the post-invasion crackdown on Russian oligarchs.

"The government is determined to see the proceeds from the sale of Chelsea Football Club reach humanitarian causes in Ukraine," the statement read. "We are deeply frustrated that it has not been possible to reach agreement on this with Mr Abramovich so far."

The UK is insisting the funds be used solely within Ukraine, aligning with broader Western efforts to hold Moscow financially accountable for the consequences of its invasion. Abramovich, however, is reportedly seeking a more flexible distribution of the funds to support victims of the war beyond Ukraine's borders.

While negotiations remain ongoing, the ministers made it clear that legal action is now a real possibility. "We are fully prepared to pursue this through the courts if required," the statement added.

Abramovich has not commented publicly on the dispute, and his legal representatives in the UK did not respond to Reuters' request for comment. According to reporting from March, the UK government had already been exploring legal pathways to resolve the impasse.

The 2.5 billion pounds from Chelsea's sale - completed in May 2022 to a consortium led by U.S. investor Todd Boehly and Clearlake Capital - is currently frozen in a UK bank account and cannot be accessed without approval from the Office of Financial Sanctions Implementation (OFSI), a branch of the Treasury tasked with enforcing sanctions.

The sale marked the end of Abramovich's highly successful but controversial tenure at Chelsea, during which the club won every major domestic and European trophy. The unresolved status of the sale's proceeds remains a cloud over the transaction, which was touted at the time as an extraordinary example of sport intersecting with global politics.

Further developments may come next week, with Abramovich expected to break nearly two decades of public silence in an on-the-record interview published in Sanctioned, a new book by journalist Nick Purewal.

UK government threatens legal action against Roman Abramovich over Chelsea sale proceeds