Caracas, Venezuela (CNN) Venezuelan opposition supporters returned to the streets on Tuesday, calling on embattled president Nicolas Maduro to let humanitarian aid into the economically crippled country.

The demonstrations come nearly three weeks after a stand-off began between Maduro and opposition leader Juan Guaido . The 35-year-old National Assembly leader has rejected Maduro's election last year as illegitimate, and declared himself the interim President of Venezuela. To the delight of his supporters, many Western nations and regional neighbors have recognized Guaido as the country's interim leader.

Maduro has remained defiant in the face of domestic and international pressure. And critically, the Venezuelan military remains loyal to Maduro.

Dueling demonstrations

In Caracas on Tuesday, a sea of colors gathered downtown as thousands emerged to share in the carnival atmosphere.

Demonstrators of all ages donned the familiar yellow, black and red of the Venezuelan flag on T-shirts, umbrellas, hats and banners.

In their hands, placards reading, "Enough! End human rights violations, yes to humanitarian aid," and "I too am another Venezuelan fighting for a free Venezuela."

An anti-Maduro protester carries a cardboard poster which reads: "Since 1/9/18 public servants have gone without health insurance. Workers are dying. Hospitals don't have medicines or supplies. SOS"

The mood among the crowd was joyful, with many families and senior citizens joining the throngs gathered despite the intense heat of the day. CNN saw several people being carried out on stretchers due to the hot temperatures.

For his supporters, Guaido appeared to be something of a rockstar, as they desperately tried to take selfies and cheered emphatically every time he spoke or his name was mentioned.

The celebratory feeling continued as the self-declared interim President appeared and announced that humanitarian aid would arrive on February 23, setting the stage for a showdown with Maduro.

He also called on all Venezuelans to help hand out the supplies.

"We will accompany all sectors: drivers, nurses, physicians, to get organized," Guaido said. "On Saturday, big assemblies, open town councils in all Venezuela will get organized."

Maduro is expected to lead a march of his own in Caracas, protesting what he has called "imperialist intervention" by the United States and other foreign governments.

In an interview with the BBC on Tuesday, Maduro said the United States is being run by the Ku Klux Klan and described President Donald Trump as a white supremacist.

"It's a political war, of the United States empire, of the interests of the extreme right that today is governing, of the Ku Klux Klan, that rules the White House, to take over Venezuela," Maduro said.

Maduro continued to deny there is a crisis in the country and denounced attempts to bring aid into the country. "Venezuela is not a country of famine. In the west, Venezuela's situation is distorted to justify any sort of intervention," he said, according to Reuters

Guaido's aid campaign

Venezuela's economic crisis has left people from all walks of life struggling for food, basic living essentials and medicine. More than three million Venezuelans have left their homes, with a million emigrating to neighboring Colombia, UNHCR said in November.

Guaido has organized a highly-publicized campaign to bring international aid to Venezuela. However, Maduro has rejected the deliveries, declaring "We are not beggars," and Reuters reports that the United Nations and Red Cross have called for both sides not to politicize aid.

"Humanitarian aid needs to be independent of political, military, or other objectives," UN spokesperson Stéphane Dujarric reportedly told press in New York.

Venezuela's self-declared leader Juan Guaido addresses crowds in Caracas on Tuesday.

Last week, two US trucks carrying food and medical supplies arrived at Venezuela's border, according to a US official in the Colombian border town of Cucuta. They found the bridge to Venezuela blocked with an orange oil tanker and two large blue containers.

UK to send aid

On Tuesday, the UK said it too would send emergency aid packages of medicine and clean water to Venezuelans.

Penny Mordaunt, the UK's International Development Secretary, said in a press release: "I am deeply disturbed by the awful scenes of suffering in Venezuela as a result of the Maduro regime's reckless mismanagement, with families resorting to eating rotting food to try to survive. UK aid will provide life-saving treatment to malnourished children, immunizations against deadly diseases and access to clean water and sanitation."

Guaido has claimed that one aid shipment already arrived in Venezuela on Monday, but did not explain where the aid originated or how it arrived in Caracas.

Later on Tuesday, Guaido shared a selfie taken at anti-government protests on his Twitter account. Alongside the photo, he wrote: "In spite of the difficulties and that we are going through the deepest crisis, we are not giving up. We are and will continue to be on the streets!"

A pesar de la dificultad y de que atravesamos la crisis más profunda, no nos rendimos.



¡Estamos y seguiremos en la calle!



Esta foto la tomé hoy, para mostrarle al mundo los rostros de la esperanza y que volvamos a creer en nosotros mismos.



¡#Vamosbien! pic.twitter.com/udYRKkCoFy — Juan Guaidó (@jguaido) February 12, 2019

"I took this picture today, to show the world the faces of hope and that we can believe in ourselves again. #Vamosbien!" he added.