He has given the US government authority to seize the wealth of immediate family members of the officials.

The order allows the government to seize any assets in the United States belonging to family members of 55 officials - including the ousted Iraqi leader - covered under an earlier presidential freeze order.

Legal technicality

The order does not actually initiate steps to seize the assets of additional individuals.

White House spokesman Claire Buchan described the action as a legal technicality bringing the United States into line with a UN resolution passed in May.