CARACAS, Jan. 31 (Xinhua) -- The United States should pay in advance for any oil it buys as a result of the U.S. sanctions on the Citgo refinery, a subsidiary of Venezuelan state-owned oil company PDVSA, Venezuela's oil minister said Thursday.

During a rally to support Venezuela's oil industry, Manuel Quevedo, who is also president of PDVSA, said that "we have no other than a ship that will set sail with Venezuelan oil, a ship that is cancelled. They want our oil? Then they'll pay for it."

The remarks were made in response to the measures taken by Washington to freeze Citgo assets worth 7 billion U.S. dollars and control Venezuela's bank accounts.

The minister accused the United States of conspiring against Venezuela and called the move "a shameless robbery."

Venezuela is currently in a difficult economic and political situation, after opposition leader Juan Guaido declared himself interim president and was recognized by the United States and some other countries.

Following Guaido's declaration, President Nicolas Maduro urged people to have "nerves of steel" and to defend the country.