Industrial and Commercial Bank of China is reportedly cooperating with the investigation into an alleged laundering of at least €40 million.

Five directors of Beijing-headquartered ICBC have been arrested after Spanish police raided the bank’s Madrid office as part of an investigation into money laundering.

The operation, dubbed "Operation Shadow", was led by the Spanish Guardia Civil, involving over 100 Spanish law enforcement officers and targeting the top management of ICBC’s Spanish branch as part of a probe into the suspected laundering of at least €40 million ($44 million), Europol, the European Union's law enforcement agency, said in a statement. 

It follows an operation last year that led to the dismantlement of a Chinese criminal network that was found to have deposited money earned into ICBC, which then allegedly sent the funds to China without checking their origin. 

“Spanish investigators found out that the money laundering system uncovered by [that] operation was employed by several other Chinese and Spanish criminal syndicates which were using the services of ICBC Spain to introduce into the financial system funds earned through the crimes of smuggling, tax and excise fraud and labour exploitation, allowing the transfer of the funds to China in a way that appeared legal,” Europol said.

A spokesman for ICBC said the bank’s Madrid branch was cooperating with the investigation, Reuters reported. 

"Strictly implementing anti-money laundering regulations, and strictly operating within the law and regulations have always been our fundamental operation and management principles," the newswire quoted the spokesman as having said.

ICBC opened a branch in Madrid in 2011 and another in Barcelona the following year. Last month, the bank expanded further with new offices in Rotterdam, the Netherlands, and Antwerp, Belgium.