James Ibori has already been acquitted of multiple corruption charges
Nigerian political powerbroker James Ibori has reportedly been freed on bail in Dubai, where he was arrested on corruption charges.
The former governor of oil-rich Delta state is accused of stealing $290m (£196m) by Nigeria's EFCC anti-corruption agency.
He has had to surrender his passport to ensure he does not leave the country, officials say.
The UK and Nigeria want to try him on corruption charges, which he denies.
Last month, a group of Mr Ibori's supporters attacked police and prevented them from arresting him in his home town of Oghara.
Some Nigerians are asking how he managed to leave the country and travel to Dubai.
Mr Ibori's spokesman Tony Eluemunor and an unamed Dubai police official said the former governor had been freed on bail.
He is a senior figure in Nigeria's ruling People's Democratic Party (PDP) and played a key role in the 2007 presidential election victory of Umaru Yar'Adua, who died last week.
Economic and Financial Crimes Commission (EFCC) head Farida Waziri told the BBC that Mr Ibori had been arrested on Wednesday following the intervention of the international police agency Interpol.
It is not clear whether he will face extradition to Nigeria or the UK.
"We are consulting on the next line of action, whether the Metropolitan Police will want him to stand trial there in London. We also have a case here pending against him," Mrs Waziri said, reports Reuters news agency.
She also said that the EFCC wanted to press new charges against him, without giving any details.
A Metropolitan Police spokesman confirmed it wanted Mr Ibori to face trial in in the UK.
In 2007 a London court froze UK assets worth $35m (£21m) allegedly belonging to him. His annual salary was less than $25,000.
He had already left the UK when his assets were seized.
He was first arrested in Nigeria in December 2007.
Two years later, a court in Asaba cleared him of 170 charges of corruption, saying there was no clear evidence to convict, sparking the anger of the EFCC.
Under Nigeria's federal system, state governors enjoy wide powers.
Those running oil-rich states have budgets larger than those of some African countries.
They enjoy immunity from prosecution while in power, but several have faced corruption charges since leaving office after the last election in 2007.