DENVER -- Qwest Communications plans to restate $531 million in revenue that was improperly recognized, the company announced Monday.

Qwest said it might also have to write down $30 billion from the lowered value of assets it bought in its 2000 acquisition of US West.

The details came in a release after the markets closed on Monday.

Last month, Qwest reversed $950 million in revenue it had booked from swaps of capacity on its fiber-optic network and said the money from capacity sales also might have to be restated.

The Securities and Exchange Commission is investigating whether fiber swaps helped Qwest artificially boost revenues.

Qwest also is the subject of a justice department investigation.