Lagos - A Nigerian court confiscated four large housing complexes worth $7m from a former oil minister accused of corruption on Tuesday as fraud investigators continue to claw back her fortune.Lagos high court judge Abdulaziz Anka ordered former petroleum minister Diezani Alison-Madueke to hand over the developments located across Nigeria that were found to have been purchased with suspect cash. Nigeria's anti-graft Economic and Financial Crimes Commission (EFCC) argued in court that Alison-Madueke, along with her cousin Donald Chidi Amamgbo, had made the purchases through front companies.During a search of Amamgbo's property, investigators also found documents indicating that he owned some 18 companies and property in Britain and the USA - as well as Nigeria.He told officers that he had registered the corporations in order to hold property on Alison-Madueke's behalf, the court heard.Amamgbo also revealed that Alison-Madueke had made mortgage payments worth more than $3.3m in cash.Since leaving office in 2015, Alison-Madueke has been implicated in bribery, fraud, misuse of public funds, and money laundering cases in Nigeria, Britain, Italy and the United States.The first female president of the global oil cartel OPEC - who was one of Africa's most prominent female politicians - has always denied the allegations, which involve billions of dollars syphoned from oil deals and state accounts. The ruling followed an application by the EFCC which earlier this month successfully confiscated a $37m luxury apartment complex from the former official.Alison-Madueke was appointed the country's first female oil minister by former president Goodluck Jonathan in 2010. She is currently on police bail in London after being arrested in connection with a British probe into international corruption and money laundering. Alison-Madueke has 14 days to appeal Tuesday's ruling.