The U.S. Treasury announced on Tuesday that it has imposed sanctions on Venezuelan President Nicolas Maduro's "inner circle," including Maduro's wife and other key government officials.

The Treasury said in a statement that it has blacklisted Venezuelan first lady Cilia Flores, Vice President Delcy Rodriguez, Communications Minister Jorge Rodriguez and Defense Minister Vladimir Padrino.

The sanctions would freeze any assets that a blacklisted person holds under U.S. jurisdiction and ban any U.S. individuals or companies from making business transactions with them.

In addition, the United States also put sanctions on a network which it accused of supporting a key front man for President of Venezuela's National Constituent Assembly (ANC) Diosdado Cabello, seizing a 20-million-U.S. dollar private jet that belonged to the front man.

The United States has been stepping up pressure on the South American country by imposing a string of sanctions, including ones on Maduro himself and the senior officials.

Venezuela has said it does not recognize any sanctions imposed on the country without UN authorization.