Venezuelan President Nicolas Maduro show his ballot as casts his vote at a polling station during the Constituent Assembly election in Caracas, Venezuela July 30, 2017. [Photo/Agencies]

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 US 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 such an announcement remained uncertain, the sources said.

Reuters