Nokia Siemens has asked a U.S. bankruptcy court to reject Ciena Corp. (Nasdaq:CIEN) as the winning bidder for Nortel Networks' optical networking and carrier Ethernet businesses and suggested it would be willing to pay more.

Nokia Siemens and its partner One Equity Partners said Tuesday they would be willing to pay $810 million in cash for the business.

The offer would top the US$530 million in cash plus US$239 million of convertible notes due June 2017 that made up Ciena's winning bid for what was considered one of Nortel's more-prized units.

In its filing with the bankruptcy court, Nokia Siemens took issue with the valuation of the convertible note portion of the offer.

Nokia Siemens, with One Equity Partners, said it had offered $770 million in cash during the auction, but Nortel picked Ciena instead.

A hearing to approve the sale of the division to Ciena is scheduled for Wednesday.

Nortel has been selling off its divisions after filing for creditor protection in January.

So far, it has sold off several pieces of the business, including its next-generation packet core network component assets to Japanese electronics manufacturer Hitachi Ltd. for US$10 million, and its enterprise solutions division to New Jersey-based Avaya for $900 million.