Venezuela's government says the US should distribute humanitarian aid in Colombia where it is being stockpiled, while the opposition warned that blocking much-needed food and medicine could constitute crimes against humanity.
A day after an aid convoy arrived in the border city of Cucuta, President Nicolas Maduro has ridiculed the US for offering small amounts of assistance while maintaining sanctions that block some $US10 billion ($A14 billion) of offshore assets and revenue.
Rival Juan Guaido, who is recognised by dozens of countries as Venezuela's legitimate leader, warned military officers against blocking the arrival of aid amid spiralling disease and malnutrition brought on by a hyperinflationary collapse.
"Take all that humanitarian aid and give it to the people of Cucuta, where there is a lot of need," Maduro said in a news conference.
"This is a macabre game, you see? They squeeze us by the neck and then make us beg for crumbs.
"They offer us toilet paper, like Donald Trump threw at the people of Puerto Rico," he said at the conference, which experienced technical difficulties including a blackout and a microphone failure.
He was referring to the US president's improvised 2018 aid distribution in the US territory following a hurricane, during which he threw rolls of paper towels.
Venezuela's dire situation has fuelled a political crisis that has peaked over the last month, with Guaido invoking a constitutional provision to declare himself the legitimate, interim president.
The 35-year-old argues Maduro was re-elected last year in a sham vote and the country must hold new presidential elections.
More than 40 nations including the US, major European powers and most of Latin America have recognised Guaido as the country's rightful head of state.
"I want to see how many military officers are willing to commit crimes against humanity by not allowing the lives of the most vulnerable to be saved, 250,000 to 300,000 are at risk of dying if they do not receive immediate attention," Guaido said during a gathering of university students.
Officials at a Cucuta warehouse organised staple foods and sanitary products into sacks during an event attended by US Ambassador to Colombia Kevin Whitaker and called on the armed forces to help it across.
The aid seems unlikely to move into Venezuela.
Humanitarian organisations have warned that attempting to force the aid into the country would be dangerous, and a top US official on Thursday said Washington did not plan to do so.
The Red Cross urged Venezuelans not to politicise the aid issue, without saying how or if the aid would arrive.
The Trump administration last week issued sweeping sanctions against state oil company PDVSA, froze profits generated by refining subsidiary Citgo, and has vowed to starve Maduro's government of all revenue.
Maduro said blocking the OPEC nation's oil shipments would be economically and socially "catastrophic" for the country, adding that anyone who accepted a nomination from Guaido to posts at PDVSA or Citgo would "face justice".
