Lawyer to former Nigerian oil minister Diezani Alison-Madueke has told a British court that she had no influence over the awarding of lucrative government contracts and was merely a "rubber stamp" for official recommendations.

The lawyer stated this on Thursday while testifying at London's Southwark Crown Court, where the former minister is facing her corruption trial.

Alison-Madueke, minister for petroleum resources between 2010 and 2015 under then-president Goodluck Jonathan, has pleaded not guilty to five counts of accepting bribes and a charge of conspiracy to commit bribery.

Prosecutors say Alison-Madueke "enjoyed a life of luxury" in London, with oil and gas industry figures having provided the use of high-end properties and given her lavish gifts to try and influence the awarding of lucrative contracts.

But her lawyer Jonathan Laidlaw told jurors that purchases were made on Alison-Madueke's behalf "because Nigerian ministers are forbidden from having bank accounts abroad", according to Reuters.

He also said Alison-Madueke, 65, disputes the extent to which properties were provided for her use and the amounts of goods she received, but that "all that was spent on her personally, in one way or another, was reimbursed".

Alison-Madueke, who was also briefly president of the Organization of the Petroleum Exporting Countries, is standing trial alongside her brother Doye Agama, 69, who has pleaded not guilty to conspiracy to commit bribery relating to his church.

Their co-defendant Olatimbo Ayinde, 54, has pleaded not guilty to one count of bribing Alison-Madueke between 2012 and 2014 and one count of bribery of a foreign public official.