By Jesús Aguado

The move was widely expected as part of the investigation into the hiring by BBVA of ex-police chief, Jose Manuel Villarejo.

News websites El Confidencial and Moncloa.com reported in January that Spain's second-biggest bank had hired Jose Manuel Villarejo's firm, Grupo Cenyt, to investigate officials of construction company Sacyr as part of efforts to stop a takeover bid by the company in 2004.

BBVA's executive Chairman Carlos Torres, in a statement on Wednesday, reiterated his "firm commitment to clarifying the facts and complying with the law, for which we will continue to collaborate actively with the judicial system."

The bank has officially acknowledged that it hired Grupo Cenyt, a security firm owned by Villarejo, who was arrested in 2017 as part of a separate investigation and remains in jail. But it says it has not found any evidence of spying.

The prosecutor said in the statement that it wanted BBVA to be put under investigation "as a legal entity for acts that would constitute offences of bribery, disclosure of secrets and corruption in business."

It added that documents seized during the investigation would prove that the hiring and allegedly illegal payments to grupo Cenyt, a security firm owned by Villarejo, affected several sensitive areas of the bank and various executives of the institution, without naming them.

It is now up to investigative judge Manuel Garcia-Castellon, who is in charge of the case, to follow up or not on the prosecutor's request.

BBVA also said in its statement that being put under investigation as requested by the prosecutor did not imply, at this preliminary stage of the probe, the formal accusation of any crime.

After the recent reform of Spain's criminal law, BBVA would at most face fines if found guilty.

BBVA has said repeatedly that it has not noticed any impact on its business from the case, which regularly makes headline news in Spain and prompted the European Central Bank to ask for a probe. But BBVA has also said the case could have a "negative reputational or economic impact."

On Monday, Torres, who replaced Gonzalez as BBVA's executive chairman in January, said in a blog to employees that the bank's own investigation into the case was "progressing well though it was subject to judicial investigation."

Earlier in July, García-Castellon expanded his investigation to eight former or current BBVA employees. None belong to the bank's current board.

(Reporting by Jesús Aguado; Editing by Ingrid Melander and Kirsten Donovan)

By Jesús Aguado