Spanish authorities have detained a close associate of the ousted Egyptian president Hosni Mubarak, Egyptian officials have said. Hussein Salem, one of the most secretive businessmen in Egypt, was detained at his home in Mallorca on an international arrest warrant issued by Interpol. He is wanted for trial in Egypt on charges of bribing Mubarak and his family and squandering public funds. The head of Egypt's Interpol office, Brigadier General Magdy el-Shafei, told the state's Middle East News Agency that authorities were preparing the necessary documents to bring Salem back to Egypt. Salem's detention was seen as a major step towards unravelling secrets of corruption throughout the reign of Mubarak, and possibly a key to locating and retrieving much of the Mubarak family's riches, believed to be stashed abroad at a time when the country's economy is depressed. Some estimate Mubarak's holdings at tens of billions of dollars.