By Jesús Aguado and Emma Pinedo

"As far as I'm concerned, there's no way I could be involved in these affairs," Torres, who took over as chairman in 2015, told journalists.

The allegations at the centre of the case date back more than 15 years and have roiled Spain's corporate sector.

News websites El Confidencial and Moncloa.com reported last year that Spain's second-biggest bank had hired Grupo Cenyt, a security firm belonging to former police commissioner Jose Manuel Villarejo, to investigate officials of construction company Sacyr as part of efforts to stop a 2004 takeover bid.

Torres said BBVA had passed of all the relevant information in the case to Spain's High Court, whose investigation is being carried out under a secrecy order.

The bank is in permanent contact with the European Central Bank, who in September asked judicial authorities in Spain for information on the probe to evaluate any potential impact on the bank's governance, Torres added.

He reiterated that the bank bore no responsibility.

The bank has officially acknowledged that it hired Grupo Cenyt. But BBVA, which is being investigated on offences of bribery, disclosure of secrets and corruption in business and is also conducting its own probe, has said it had not found any evidence of spying.

While Torres said the case has had no impact on the bank's business or its reputation, it was in the bank's interest to see the case resolved as soon as possible and with full transparency.

"If the secrecy (of the case) is lifted we would be closer to the end of the investigation (...) the sooner the better," Torres said.

No members of the current board have been put under investigation regarding the case.

When asked if he or any board member would step down if the probe was extended to include them, Torres said there were no mechanisms in place regarding that outcome and dismissed any potential implications as speculation.

"What we would have to ensure is that anyone holding a position is suitable for that position in every case (...) but that scenario is a speculation," Torres said.

(Reporting By Jesús Aguado and Emma Pinedo; writing by Ashifa Kassam; editing by Inti Landauro and Louise Heavens)

By Jesús Aguado and Emma Pinedo