* Ibori tried to bribe anti-corruption boss Ribadu
* Bag of cash handed over at home of close presidential aide
* Ribadu tells court money was secured at central bank
* Says Ibori "wasted or stole" over $500,000,000 as governor
By Estelle Shirbon
LONDON, Sept 19 (Reuters) - Desperate to halt a probe into his finances, Nigerian governor James Ibori tried to bribe anti-corruption boss Nuhu Ribadu in 2007 with $15 million in cash in a bag so heavy one man alone could not lift it, Ribadu told a London court on Thursday.
Ribadu said he pretended to take the bribe because he wanted the cash as evidence to use against Ibori in a prosecution, but rather than keep the money for himself he had it taken straight to the Central Bank of Nigeria to be kept safe in a vault.
Ibori was governor of oil-producing Delta State in southern Nigeria from 1999 to 2007. In 2012, he pleaded guilty at London's Southwark Crown Court to 10 counts of fraud and money-laundering and was jailed for 13 years.
He is the most senior Nigerian politician to be held to account for the corruption that has for decades held back Africa's most populous nation and top oil producer.
Ribadu told the court that about $1 billion flowed from federal government accounts into Delta State coffers during Ibori's eight years in power, and he estimated Ibori had stolen or wasted more than half of that amount.
The charges to which Ibori pleaded guilty amount to the theft of about $80 million, but British prosecutors say that was only part of his total booty, which was kept hidden via a complex web of shell companies, offshore accounts and front men.
Ribadu, who was chairman of Nigeria's Economic and Financial Crimes Commission (EFCC) from April 2003 to December 2007, was giving evidence at a confiscation hearing in which prosecutors are seeking court orders to have Ibori's assets seized.
Under Nigeria's constitution, state governors enjoy immunity from prosecution but are limited to two terms in office. With the end of his second term looming in April 2007, Ibori was worried the EFCC were planning to prosecute him, Ribadu said.
"He was very desperate to terminate the investigation," he told the court.
In late April 2007, a meeting was arranged between the two men at a "neutral place", the house of Andy Uba, a close associate of outgoing President Olusegun Obasanjo.
Ibori arrived at the house with several members of his staff and a very large black sack containing $15 million in cash. Ribadu said he watched as two of Ibori's men lifted the heavy sack and handed it over to his own EFCC staff. "It was a bag that an individual could not carry alone," he said.
The EFCC men drove the bag to the central bank where the money was counted and boxed into smaller containers. The court was shown photographs of the boxes of cash.
"I have given you money Nuhu, just give me my clearance," Ribadu quoted Ibori as telling him after those events.
Instead, the EFCC continued to investigate Ibori's affairs and had him arrested on corruption charges on Dec. 12, 2007.
But Ribadu said the climate had changed since Obasanjo had stepped down and President Umaru Yar'Adua had been sworn in. Ribadu said Ibori was close to Yar'Adua, and the new attorney general Michael Aondoakaa sought to neuter the EFCC.
On Dec. 27, just 15 days after Ibori's arrest, Ribadu was sacked as chairman of the EFCC. Efforts to prosecute Ibori in Nigeria foundered, and he was eventually prosecuted in Britain because he had laundered some of his millions there.
After his removal as EFCC chairman, Ribadu told the court he survived two separate assassination attempts including one during which three shots were fired at his car.
After the second attempt, he fled Nigeria by what he described as the "bush path", first by motorcycle taxi across the border to Benin, then by an Air France flight to Paris and then to Britain where he was given refuge at an Oxford college.
Ribadu remained in exile until after the death of Yar'Adua in May 2010. He told the court that under new President Goodluck Jonathan, the climate changed again and he returned home.
It was also that year that Ibori's luck turned. He was arrested in Dubai on a British warrant and extradited to London a year later. He is now serving his term at Long Lartin maximum security prison in central England. (Editing by Alison Williams)