Carlos Torres, CEO of Spanish bank BBVA, said blockchain technology is “not mature” and faces major challenges, el Economista reported June 18.

Torres expressed his concerns about blockchain’s current limitations at an event organized by the Spanish Association for Economic Journalism which focused on the prospects of the technology.

According to Torres, the main challenges for blockchain are the “volatility of underlying currencies” and possible compatibility issues with tax authorities and financial regulators.

Despite its contemporary challenges, Torres said that the advantages of blockchain technology are so important to their business, that “when it is mature and regulators are ready,” BBVA wants to have the tools necessary to apply the technology to relevant use cases, such as syndicated loans.

Torres added that, given blockchain’s potential, there should be adequate, unrestricted, but supervised spaces for developing the technology.

Banco Bilbao Vizcaya Argentaria (BBVA) is a northern Spanish bank founded in Bilbao in the late 19th century. According to an Economipedia report, BBVA was Spain’s second largest bank by assets and capitalization in 2017.

In April, BBVA became the first global bank to issue a loan using blockchain technology. BBVA conducted the entire process of a €75 million loan, from the negotiation of terms to signing, on a distributed ledger.

Issuing the loan using blockchain technology reportedly cut the time needed to complete the process from “days to hours.” At the time, Torres said that the bank had “several more transactions in the immediate pipeline,” and that BBVA would be launching a pilot program with Spanish telecoms firm Indra. Indra has described itself as “at the vanguard” of blockchain applications.