Facebook's upcoming cryptocurrency project Libra has plenty of doubters. Add Mark Cuban to the list.

On Friday, Cuban spoke out against the Facebook initiative, calling it "a big mistake" in comments to CNBC. "I think globally and in countries where there isn't a lot of rule of law, or a lot of government stability, or currency stability, then it could be dangerous," the Shark Tank investor said. "There's going to be some despot in some African country that gets really upset that they can't control their currency anymore and that's where the real problems start occurring."

Cuban joins a growing chorus of high-profile voices against Libra, which was announced by Facebook last month and is set to launch in mid-2020. Members of the U.S. Congress expressed concern almost immediately, and on Wednesday, U.S. Federal Reserve chair Jerome Powell told a congressional committee that "Libra raises serious concerns regarding privacy, money laundering, consumer protection, financial stability."

International regulators from Financial Stability Board chair Randal Quarles to French finance minister Bruno Le Maire and Bank of England governor Mark Carney have been equally candid about their uneasiness. Meanwhile, some of Facebook's Libra partner companies--which include Uber, PayPal, Visa, and Mastercard--reportedly signed non-binding contracts and have yet to spend any money on the project.

Hearings on Libra in the U.S. Senate and U.S. House of Representatives are scheduled for July 16 and July 17, respectively.