President Donald Trump's administration is considering imposing some U.S. sanctions on Venezuela's vital oil sector in response to Sunday's election of a constitutional super-body that Washington has already denounced as a "sham" vote, U.S. officials said.

The measures, which could be announced as early as Monday, are not expected to include a ban on Venezuelan oil shipments to the United States -- one of the harshest options -- but could block sale of lighter U.S. crude that Venezuela mixes with its heavy crude and then exports, the officials told Reuters.

While no final decisions have been made, the officials, who spoke on condition of anonymity, said the United States could also sanction further senior Venezuelan officials. But the timing of any new sanctions, which were imposed on 13 Venezuela figures last week, remained uncertain.

Other options that remain under consideration, the officials said, are various measures to restrict access by the Venezuelan government and state oil company PDVSA to the U.S. banking system, the sources said. But it was not clear whether the U.S. administration was ready to take such action or would instead hold it in reserve if further escalation was deemed necessary.

The new round of sanctions is intended to make good on Trump's threat of "strong and swift economic actions" if Venezuelan President Nicolas Maduro went ahead with Sunday's election of a controversial new congress, the officials said.

But the U.S. response, though expected to be the toughest yet against Maduro's leftist government since Trump took office, is also being calibrated to avoid causing further suffering to the Venezuelan people or damaging U.S. economic interests, the officials said.

The White House did not immediately respond to a request for comment.