The Mexican Congress has launched special investigations into two of the closest allies of President Vicente Fox first lady Marta Sahagún de Fox and former interior secretary Santiago Creel in a move could also have a significant impact on next year's presidential election.

One committee will investigate Ms Sahagún's sons by her first marriage, who appear to have become much richer under Mr Fox's presidency. Another will investigate Mr Creel's decision to award 198 new casino licences in his last week in office before standing down to seek the presidency, in a move that was allegedly to curry favour with potential campaign donors.