* Banks say they face logistical problems with data
ECB indicated it won't alter asset test schedule - sources
* ECB review will feed into EU-wide stress tests
* Exercises may force some banks to raise more cash
* Spanish banks fear test scenarios will be too harsh
(Adds Spanish bank concerns, Dimon quotes)
By Laura Noonan and Gianluca Semeraro
LONDON/MILAN, April 9 (Reuters) - The European Central Bank has dismissed the latest appeal by the region's biggest lenders for concessions, including easier deadlines, to make rigorous health checks of their industry less logistically onerous, sources told Reuters.
ECB officials indicated to representatives of the European Banking Federation, an industry lobby group, that they would not alter the timetable of this year's "asset quality review", two sources familiar with a meeting between the two sides said.
The meeting, held in Frankfurt on Tuesday, marked the latest attempt by euro zone banks to get changes to the ECB exercise which will feed into stress tests across the European Union to ensure that lenders could survive a future crisis without needing taxpayer-funded bailouts.
"There was nothing new from the ECB on the ... process at (the) meeting and no indication of flexibility on timelines," one source familiar with the discussions told Reuters.
The ECB declined comment while a Brussels-based spokesman for the EBF, which represents national banking associations from across Europe, said it did not comment on specific meetings.
Federico Ghizzoni, CEO of Italian bank UniCredit, said on Tuesday night that he did not know the outcome of the discussions, but his impression was that the ECB would not modify its requests for data.
"There was an operational meeting concerning the difficulties of meeting the deadlines to submit the data for the asset quality review, an issue raised not only by Italian but also by European banks," he told reporters in Milan.
"It is a logistical difficulty arising from the amount of data and the time frame, it is not about contents," he said.
Bankers say they do not want to water down the landmark review of whether the euro zone's 128 largest lenders have properly valued their assets, but need more time in preparing for the complex process.
The ECB has repeatedly insisted there will be no slippage from its plan to complete the review by October, which would ensure any skeletons in the closet are dealt with before it takes over as the euro zone's bank supervisor in November.
The stress tests could force some banks to raise more cash to prove they can withstand another downturn without the kind of state rescue a number needed during the financial crisis which exploded in 2008. The aim of both sets of tests is to restore confidence in European banks, whose shares remain valued at a significant discount to their U.S. rivals.
Spanish lenders fear that excessively harsh economic scenarios could be used in assessing their strength. "The stress tests need to be based on plausible scenarios," Banco Popular Chairman Angel Ron told shareholders earlier this week, echoing similar comments from Bank of Spain deputy governor Fernando Restoy.
Speculation is growing that the scenarios may include a far deeper recession than the actual 3 percent drop in Spanish gross domestic product between mid-2010 and mid-2013, as well as a leap in unemployment from the current rate of 26 percent, which along with Greece's is already the highest in the euro zone.
Such scenarios would create major hurdles for Spanish banks, some of which took state bailouts following a property market crash. The Bank of Spain declined comment and the European Banking Authority (EBA), which is conducting the EU-wide tests, said the scenarios would be disclosed by the end of April.
The EBA-approved scenarios are minimum standards EU banks will be tested against, but national authorities have the power to toughen them further for their own lenders.
Unlike in the United States, where banks were given a thorough examination followed by recapitalisation in 2009, European peers have undergone only half-hearted assessments until now, and their problems are holding back economic growth.
Jamie Dimon, chief executive of JPMorgan Chase & Co, said the U.S. banking industry had almost completely recovered from the global crisis. "It can now do its job: financing growth and employment. Unfortunately, Europe is not yet at the same stage," he told French newspaper Le Figaro.
A 285-page manual setting out how assets will be examined was published on March 11. But banks say the ECB's request for data, which can run to more than a hundred fields per loan file, are too onerous. Questions about some of the ECB's methodology were also raised at an earlier meeting on March 26 between ECB officials and senior executives from the 128 banks.
One source said those issues were also raised at Tuesday's EBF meeting, but no progress was made.
"They take their manual as the Bible," said an attendee of the March 26 meeting. "There is no world beyond the manual."
The EBF said it backs the overall exercise. "It is a challenging process that is an essential step towards the construction of the single supervisory and resolution mechanisms," the spokesman said. "The EBF, as representative of European banks, fully supports this complex process."
(Additional reporting by Sarah White and Jesus Aguado in Madrid and Maya Nikolaeva in Paris; editing by David Stamp)