US-based investment bank Merrill Lynch says it will be forced to write off another $6 billion because of its exposure to high-risk mortgages.

Merrill Lynch has moved to sell $30 billion of risky debt as it tries to steady its troubled balance sheet.

The bank has also revealed it expects to write-off another $6 billion of mortgage-related debts in this current financial quarter.

The announcement comes just a week after Merrill Lynch posted a quarterly loss of $5 billion.

The Bank has also been forced to seek $9 billion in fresh capital to help it deal with the continuing credit crisis.

Analysts expect further write-downs from other big investment banks in coming weeks.