Venezuela's vice president is visiting Russia, seeking stronger ties with Moscow amid mounting pressure from the United States.

Venezuela's ruling party has installed a new super assembly that supporters promise will bring peace to the country and critics fear will be a tool for imposing dictatorship.

The US has slapped new sanctions on eight members of Venezuela's Supreme Court, accusing them of abusing power and damaging their nation's democratic fabric as the Trump administration raises concerns that socialist president Nicolas Maduro is moving toward one-party, authoritarian rule.

At least 12 people have been killed following looting and violence in Venezuela's capital amid a spiralling political crisis in the South American country.