The United States slapped economic sanctions on eight Venezuelan politicians linked to the creation of a controversial new assembly loyal to President Nicolas Maduro, including a brother of former president Hugo Chavez.

"President Maduro swore in this illegitimate Constituent Assembly to further entrench his dictatorship, and continues to tighten his grip on the country," said Treasury Secretary Steven Mnuchin.

"This regime's disregard for the will of the Venezuelan people is unacceptable, and the United States will stand with them in opposition to tyranny until Venezuela is restored to a peaceful and prosperous democracy."