May.14, 2010, 12:56 AM BST

James Ibori, 47, a former governor of oil-rich Delta state, is wanted for questioning in Britain over suspicious transactions worth tens of millions of pounds made through British banks and offshore companies.

The High Court froze $35 million (£23.7 million) in cash and assets owned by Mr Ibori in 2007.

A spokesman for the Metropolitan Police confirmed that it would seek Mr Ibori's extradition. No charges have been laid against Mr Ibori but several alleged associates have faced trial. Mr Ibori's wife Theresa, who is a UK citizen, has also been questioned.

Diplomatic observers said attempts to prosecute Mr Ibori have been some of the longest, most complex and expensive operations mounted by Scotland Yard in recent years. Prosecutors allege that companies owned by Mr Ibori and his family were beneficiaries from the sale of state assets, including shares in a mobile telephone operator, as well as crude oil deliveries.

Mr Ibori is alleged to have used UK banks to launder the proceeds to his own personal accounts during his period in office.

Nigeria's anti-corruption body, the Economic and Financial Crimes Commission (EFCC) tried and failed to prosecute Mr Ibori on separate charges of $85 million (£57.6 million) allegedly looted from the Delta State treasury between 1999 and 2007, when he was governor.

His close ties to Umaru Yar'Adua, the former president who died last week, provoked a storm of controversy in Nigeria. Nigeria is desperately poor despite possessing Africa's largest deposits of oil. Generations of politician have siphoned off billions of pounds from oil revenues to their own benefit.

Mr Yar'Adua sacked Nuhu Ribadu, the head of the EFCC, after 170 charges were brought against Mr Ibori. A court dismissed those cases last December.

Nigeria newspapers have alleged that Mr Ibori had bought luxurious homes in Hampstead, a number of expensive cars and other trappings of luxury.

Mr Ibori disappeared from Nigeria last week after a large crowd thwarted an attempt by Nigerian police to rearrest the former governor. The authorities there said they would defer to the British police application.