Spanish prosecutor seeks extradition of JPMorgan "London Whale" supervisor

* Javier Martin-Artajo attends court hearing in Madrid

* The ex-JPMorgan banker was supervisor of "London Whale"

* Faces extradition request from United States

* Court ruling pending, prosecutor supports extradition

By Jesús Aguado

MADRID, March 5 (Reuters) - A Spanish prosecutor has recommended extradition to the United States of Javier Martin-Artajo, an ex-JPMorgan Chase & Co (Xetra: 850628 - news) executive indicted over the "London Whale" scandal which led to over $6.2 billion in trading losses at the bank in 2012.

Spaniard Martin-Artajo, who was the London supervisor of Bruno Iksil, nicknamed the London Whale for his big derivatives bets, is resisting extradition and told the High Court in Madrid on Thursday he was innocent.

But the prosecutor told the court she thought there were grounds for the extradition to be granted and that Martin-Artajo had allegedly helped cover up $767 million in trading losses.

The court has to give its opinion on the request but Spain's government has the last say. The ex-banker is accused of helping to hide trading losses and would face charges of wire fraud and conspiracy to defraud.

"I consider myself innocent, because I could not have done this ... nor did I do it," Martin-Artajo, wearing a white open-necked shirt and dark suit, told a public hearing at the court. "I have no reason to do any of the things I am accused of."

He argued that the charges he faced, which could carry prison sentences of up to 95 years, were disproportionate and that the trading losses had in any case occurred in London.

His defence team had long been expected to argue that the United States had no jurisdiction over the case.

Martin-Artajo was arrested in Madrid last year and granted a conditional release. He is the most senior figure detained over the case, while Iksil, who cooperated with U.S. authorities, has not been charged.

The London Whale scandal was an embarrassment for JPMorgan though its boss Jamie Dimon famously initially dismissed it as a "tempest in a teapot". More recently in December the bank outlined improved controls, describing for instance how it clawed back or canceled more than $100 million in executive compensation after the London Whale affair.

(Writing by Sarah White; Editing by David Holmes)