Kevin Weil, VP of product at Facebook's Calibra, speaks on stage at the Web Summit technology conference in Lisbon, Portugal on November 5, 2019.

LISBON, Portugal — A top Facebook executive has said the tech giant's proposed libra cryptocurrency won't go viral like a social media platform and will take decades to roll out.

"This is not going to be a thing that spreads like a social network," Kevin Weil, vice president of product at Facebook's Calibra digital wallet unit, told an audience at the Web Summit technology conference. "This is going to be the work not of years but of decades, and it's worth making."

The company has come under intense regulatory pressure ever since it first announced its plans for a digital currency back in June. The Libra Association, a Switzerland-based consortium overseeing the project, lost multiple key initial backers including Mastercard and Visa last month on the back of that pushback.

But Weil seemed optimistic on the interest among other companies in joining Libra. "18 months ago, this was an idea," he said. "Today we have 21 fantastic committed organisations that are members of the Libra Association; a bunch more that are looking to be involved. So expect that number to continue to grow."

Libra's value would be tied to a basket of government currencies and debt to maintain a stable value, similar to the many so-called "stablecoins" that look to avoid the volatility seen in cryptocurrencies like bitcoin. Facebook says its primary use case would be for remittances, where people send money across borders.