Spanish national Javier Martin-Artajo told Spain's National Court that he did not consent to be extradicted voluntarily to face charges because the crimes he is accused of took place in Britain not in the United States and because he has roots in Spain, a court source told AFP.
"He also asked the judge to request more information about the case from the United States," the source added.
If the judge requests more information, the United States has 30 days to reply, the source said.
Martin-Artajo is accused of being the senior figure in the 2012 trading scandal involving US$6.2 billion (€4.6 billion) in trading losses at the US banking giant.
US federal prosecutors in August filed criminal charges against Martin-Artajo and another former JPMorgan employee, Frenchman Julien Grout, alleging they kept false records on trades, committed wire fraud and submitted false US securities filings when they worked for the bank in London.
A third ex-JPMorgan banker, French national Bruno Iksil – originally identified as the "London Whale" responsible for the trades – was cleared of criminal responsibility after cooperating with prosecutors.
Spanish police arrested Martin-Artajo Rueda on August 27th on an international warrant and released him on condition that he check in with the National Court every two weeks and remained in Spain pending a ruling on extradition.