Former Nigerian petroleum minister Diezani Alison-Madueke on Monday denied bribery allegations in her ongoing trial at Southwark Crown Court in London, insisting she never solicited or received illicit payments while in office.

She faces five counts of accepting bribes and one of conspiracy to commit bribery. She was charged in 2013, with prosecutors alleging she benefited from millions in luxury spending funded by businessmen seeking government contracts.

Prosecutors claim businessmen financed her lavish expenses, including £2 million spent at Harrods and £4.6 million spent on refurbishing properties in London and Buckinghamshire. UK investigators describe the case as part of a “major international corruption probe,” with parallel asset recovery efforts in Nigeria and the US.

In her defense, the former minister denied wrongdoing, stating that “at no point did I ask for, take or receive a bribe of any sort.” She claimed she “tried to push back on corruption” in Nigeria, which she described as a systemic issue dating back to colonial times. She also argued that expenses incurred on her behalf during official engagements were reimbursed by the Nigerian National Petroleum Company Limited and some properties cited by the prosecutors were meant for official functions.

Alison-Madueke served as Nigeria’s petroleum minister from 2010 to 2015 under the administration of former president Goodluck Jonathan. She was also the first female chairman of the Organization of the Petroleum Exporting Countries (OPEC) in 2014 to 2015.