The island where Roman Abramovich is suspected of holding $7 billion in assets has reportedly opened a probe into his wealth

According to a Tuesday report from The Wall Street Journal, Jersey, the largest of the UK's Channel Islands, has opened a probe into Roman Abramovich's off-shore wealth.

People familiar with the situation told the outlet that the probe will look into potential sanctions evasion and how the billionaire acquired the oil company.

Russia's former chief prosecutor called the deal in which Abramovich bought a stake in a Russian oil company for $250 million and sold it back a decade later for $13 billion fraudulent. The billionaire is worth $12.6 billion.

The government of Jersey wouldn't comment on or confirm reports of a probe.

Around a month after the UK imposed sanctions on the Russian billionaire, the royal court of Jersey froze more than $7 billion of his assets. According to a statement released last month, authorities executed search warrants at locations around the island believed to be connected to Abramovich's business activities.

The overseas territory is not an official part of the UK. Jersey does not have capital gains or inheritance tax, making it a popular destination for the superrich.

Jersey was ranked as one of the worst tax havens in the world by the Tax Justice Network. The government said the state is in full compliance with international standards. The EU does not categorize Jersey as a non-cooperative jurisdiction for tax purposes.