XL Capital has increased its acknowledged exposure to collateralised debt obligations (CDOs) by $600 million after reviewing its definition of certain securities that were not previously included in its methodology.

As a result XL now estimates its total exposure to CDOs is $1.4 billion and not the $800m figure mention in last week's second quarter conference call.

Credit risk vehicles, particularly anything that is linked to subprime mortgages in the US, are increasingly under the spotlight.

However, XL has pointed out that the reclassification of certain asset-backed securities had no impact - as of June 30 - on the company's overall exposure to subprime which is put at approximatly $1.2bn and XL's asset-backed CDO exposure with a subprime component is around $100m.

The amount of lower grade BBB-rated securities within XL's total $1.4bn of CDOs is extimated at 20 percent.