The UK National Crime Agency [NCA] on Saturday said investigation into allegations of corruption against Nigeria’s former minister of Petroleum Resources, Diezani Alison-Madueke, and the four other people arrested Friday had been on since 2013.

In an update on its website, the NCA said, “The investigation commenced in 2013 under the Proceeds of Corruption Unit, and transferred to the NCA earlier this year.”

Until recently, the Proceeds of Corruption Unit was domiciled at the Metropolitan Police Service.

But after the International Corruption Unit was created at the NCA in line with the UK Anti-Corruption Plan, the Proceeds of Corruption Unit at the Metropolitan Police and the Overseas Anti-Corruption Unit of the City of London Police were scrapped.

The ICU then became the UK’s prime agency  for the investigation of bribery of foreign public officials by individuals or companies from the UK, and money laundering by corrupt foreign officials and their associates.

In its update Saturday, the NCA also said it had released the former minister on “conditional bail”.

The other four unnamed persons arrested with her were also granted bail.

“All five people arrested were released on conditional police bail later that evening, pending further investigation both in the UK and overseas.”

The conditions of the bail are not immediately clear.

But people familiar with the matter told PREMIUM TIMES that Mrs. Alison-Madueke and her colleagues were barred from travelling out of the UK pending conclusion of investigation and their arraignment in court.

One source said the suspects’ travelling documents were seized, but PREMIUM TIMES has been unable to independently verify that as at the time of this report.

The source also said the suspects were also warned against any attempt to tamper with evidence.

PREMIUM TIMES had on Friday exclusively reported the arrest of the former minister, alongside four others, by the UK agency over offences related to bribery, corruption and money laundering.

The identities of the four other people arrested along with Mrs. Alison-Madueke, could not be immediately ascertained.

Former minister accused of graft

​Mrs. Alison-Madueke, one of the most influential officials of the President Goodluck Jonathan administration, was first appointed into the federal cabinet in 2007.

A former board member of Shell Petroleum Development Company of Nigeria, she was later appointed Minister of Transport by former President Umaru Yar’adua.

In December 2008, she was redeployed to the mines and steel development ministry.

After former Vice President Goodluck Jonathan became acting president, Mrs. Alison-Madueke was appointed Nigeria’s first female petroleum minister in February 2010, a position Mrs. Alison-Madueke held till May 29, 2015 when Mr. Jonathan left office.

Mrs. Alison-Madueke’s tenure as petroleum minister turned out one of Nigeria’s most controversial, amid unending allegations of massive corruption.

Under her watch, dubious oil marketers stole trillions of naira of oil subsidy money. She retained her position despite an indictment by the House of Representatives which investigated the fuel subsidy scandal.

Probes by independent audit firms, including the KPMG and PriceWaterhousecoopers, confirmed that billions of dollars of oil money were missing. The most notable case of missing money involved $20billion in 2014, as alleged by a former Central Bank governor, Lamido Sanusi.

Several shady deals exposed by PREMIUM TIMES and confirmed by government and independent auditors were linked to the former minister and her cronies.

Long before her stint in the oil and gas sector, Mrs. Alison-Madueke was investigated by the Nigerian Senate on allegation she paid N30.9 billion to contractors while she held office as transportation minister.

In 2009, the Senate indicted and recommended her prosecution for allegedly transferring N1.2 billion into a private account of a toll company without due process.

Regardless of the indictments, Mrs. Alison-Madueke got elected in November 2014 as the first female president of oil producing countries alliance, OPEC.

The former minister consistently denies wrongdoing. In June, after leaving office, she rejected all allegations of embezzlement saying she never stole from Nigeria.