US banking giant Citigroup, which is expanding its consumer lending business, is buying ABN Amro's Mortgage Group for an undisclosed sum. ABN Amro's mortgage arm provides residential mortgages in the US.

The acquisition includes assets worth $9 billion and a mortgage portfolio of $224 billion.

The deal, due to be completed by March end, would add 1.5 million servicing customers to its mortgage business and enable The acquisition will enable Citigroup to move from fifth place to fourth in the mortgage servicing market.

Last week, Citigroup reported a 26 per cent drop in quarterly net profits to $5.13 billion.