They were detained overnight and while three of them can be freed if they post bail of 100,000 euros (USD 111,000) each, the others will remain in custody for the time being, the Madrid appeals court said.
The suspects were arrested on Wednesday at the bank's central Madrid branch as part of a probe into the suspected laundering of at least 40 million euros (USD 44.5 million).
They were questioned from yesterday afternoon through to early today.
Spanish prosecutors said the employees were being sought for "economic crimes" but did not elaborate.
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The raid was a follow-up to an operation last year that targeted Madrid-based Chinese syndicates suspected of importing huge amounts of goods from China without declaring them, to avoid duties and taxes.
The groups allegedly deposited the proceeds in ICBC accounts, with the lender accused of sending the funds to China without checking their origin as required by law.
The Chinese lender's foreign operations accounted for about 10 percent of its total assets at the end of last year.