The US and other countries that have recognized Guaido as interim president have pledged humanitarian aid, amid questions over how it can be distributed without the military's support.

"We have received information, from the circle close to the high command, who are no longer evaluating if they let it enter or not, but how they will steal it from us," Guaido told reporters in Caracas.

"They are going to hijack it to distribute it through the CLAP," he alleged, referring to the socialist government's program to distribute subsidized food boxes to its supporters.

Guaido said he was appealing to the military's "conscience" to let the aid pass into the country to those who most need it.

Maduro has refused to accept humanitarian aid, dismissing it as a precursor to US military intervention.

Guaido confirmed that aid is being stockpiled in Colombia, Brazil and on an unidentified Caribbean island, amid plans to transport it to Venezuela.

The opposition leader said the proposed aid shipments would be prioritized for the "most vulnerable" people. He said earlier that between 250,000 and 300,000 Venezuelans were at risk of death due to malnutrition and lack of medicines and supplies.

He called for a "large mobilization to safeguard this humanitarian aid," though he did not specify a date for such a protest.