Venezuelan president Nicolas Maduro has closed the nation’s border with Brazil, amid an escalating standoff over allowing aid from the US to enter the country.

In a televised address from the nation’s largest military base, Mr Maduro said he was also considering shuttering the border with neighbouring Colombia, two days before the opposition has vowed to move aid from the US and other nations inside Venezuela.

“I don’t want to take any decision of this type but I am evaluating it, a total closure of the border with Colombia,” he said.

Some Venezuelans crossed over into the Brazilian city of Pacaraima to stock up on supplies shortly before the border was closed late Thursday night, according to Brazilian media.

Earlier on Thursday opposition leader Juan Guaido set off for the border with Colombia, where much of the US-supplied aid is warehoused.

Venezuelans make art from banknotes in bid to give them value Show all 13 1 /13 Venezuelans make art from banknotes in bid to give them value Venezuelans make art from banknotes in bid to give them value venezuela-currency-3.jpg FILE - In this Feb. 6, 2019 file photo, Venezuelan migrant Edixon Infante shows a handicraft made in with devalued Venezuelan currency, in Cucuta, Colombia. The Venezuelan government and its state-owned entities currently owe around $150 billion to creditors around the world, while the countryÃ¢â¬â¢s foreign currency reserves have fallen to just $8 billion. (AP Photo/Fernando Vergara, File) AP Venezuelans make art from banknotes in bid to give them value venezuela-currency-1.jpg A Venezuelan migrant shows handicrafts made in with devalued Venezuelan currency, in Cucuta, Colombia, Wednesday, Feb. 6, 2019. The Venezuelan military blocked a border bridge where humanitarian aid is expected to arrive with a tanker and two cargo trailers, Colombian officials said Monday, in an apparent bid to stop the loads of food and other supplies from entering the country. (AP Photo/Fernando Vergara) AP Venezuelans make art from banknotes in bid to give them value venezuela-currency-2.jpg Venezuelan migrant Edixon Infante shows his handicrafts made in with devalued Venezuelan currency, in Cucuta, Colombia, Wednesday, Feb. 6, 2019. Tensions in the area have risen since the Venezuelan military blocked a border bridge where humanitarian aid is expected to arrive with a tanker and two cargo trailers, Colombian officials said Monday, in an apparent bid to stop the loads of food and other supplies from entering the country. (AP Photo/Fernando Vergara) AP Venezuelans make art from banknotes in bid to give them value venezuela-currency-5.jpg Closeup of a purse made by Venezuelan Wilmer Rojas, out of Bolivar banknotes in Caracas on January 30, 2018. - A young Venezuelan tries to make a living out of devalued Bolivar banknotes by making crafts with them. (Photo by FEDERICO PARRA / AFP) / TO GO WITH AFP STORY by Margioni BERMUDEZ (Photo credit should read FEDERICO PARRA/AFP/Getty Images) AFP/Getty Venezuelans make art from banknotes in bid to give them value venezuela-currency-4.jpg Detail of a bag made with Bolivarian money seen in the La Parada neighborhood in Cucuta, Colombia, near the Simon Bolivar International Bridge, on the border with Tachira, Venezuela, on February 9, 2019. - Venezuelans cross to Colombia to buy groceries due to the shortages in their country. Venezuelan President Nicolas Maduro vowed on Friday not to let in "fake" aid from the United States requested by opposition leader Juan Guaido, which is being stockpiled at the border with Colombia. (Photo by Raul ARBOLEDA / AFP)RAUL ARBOLEDA/AFP/Getty Images AFP/Getty Venezuelans make art from banknotes in bid to give them value venezuela-currency-6.jpg Wilmer Rojas, 25, shows the purses he sewn up, using Bolivar bills in Caracas, on January 30, 2018. - A young Venezuelan tries to make a living out of devalued Bolivar banknotes by making crafts with them. (Photo by FEDERICO PARRA / AFP) / TO GO WITH AFP STORY by Margioni BERMUDEZ (Photo credit should read FEDERICO PARRA/AFP/Getty Images) AFP/Getty Venezuelans make art from banknotes in bid to give them value venezuela-currency-8.jpg Torn apart Venezuelan two-Bolivar banknotes lie in a street of Caracas on January 28, 2019. - Venezuela devalued its currency by almost 35 percent on Monday to bring it into line with the exchange rate of the dollar on the black market. The exchange rate is now fixed at 3,200 bolivars to the dollar, almost matching the 3,118.62 offered on the dolartoday.com site that acts as the reference for the black market. (Photo by YURI CORTEZ / AFP) (Photo credit should read YURI CORTEZ/AFP/Getty Images) AFP/Getty Venezuelans make art from banknotes in bid to give them value venezuela-currency-9.jpg CARACAS, VENEZUELA - FEBRUARY 02: A woman holds a sign that reads 'No more dictatorship' during a rally against the government of NicolÃ¡s Maduro in the streets of Caracas on February 2, 2019 in Caracas, Venezuela. Venezuela's self-declared president and accepted by over 20 countries, Juan Guaido, called Venezuelans to the streets and demands the resignation of NicolÃ¡s Maduro. (Photo by Marco Bello/Getty Images) Getty Venezuelans make art from banknotes in bid to give them value venezuela-currency-7.jpg CARACAS, VENEZUELA - FEBRUARY 02: People shout slogans during a rally against the government of NicolÃÂ¡s Maduro in the streets of Caracas on February 2, 2019 in Caracas, Venezuela. Venezuela's self-declared president and accepted by over 20 countries, Juan Guaido, called Venezuelans to the streets and demands the resignation of NicolÃÂ¡s Maduro. (Photo by Marco Bello/Getty Images) Getty Venezuelans make art from banknotes in bid to give them value venezuela-currency-10.jpg CARACAS, VENEZUELA - JANUARY 30: A woman holds a banner that reads "No more deaths due to lack of medicines" during a demonstration against the government of President NicolÃ¡s Maduro called by the opposition leader self-proclaimed âacting presidentâ Juan Guaido on January 30, 2019 in Caracas, Venezuela. Guaido is appealing international leaders and military forces to recognize him as the rightful president of Venezuela. (Photo by Marco Bello/Getty Images) Getty Venezuelans make art from banknotes in bid to give them value venezuela-currency-15.jpg A man cleans his stall selling hot dogs and hamburgers with new grocery prices in Caracas, Venezuela on January 15, 2019. - The president of Venezuela, NicolÃ¡s Maduro, increased the minimum wage by 300% Monday, a measure that was accompanied by a devaluation of 9.18% of the local currency, the bolivar. The new minimum income reaches two kilos of meat, in the middle of a hyperinflation that -according to the IMF- will reach 10,000,000% this year. (Photo by YURI CORTEZ / AFP) (Photo credit should read YURI CORTEZ/AFP/Getty Images) AFP/Getty Venezuelans make art from banknotes in bid to give them value venezuela-currency-14.jpg TOPSHOT - A man holds a cardboard with empty packages of different products and their prices, during a mass opposition rally against leader Nicolas Maduro in which Venezuela's National Assembly head Juan Guaido (out of frame) declared himself the country's "acting president", on the anniversary of a 1958 uprising that overthrew a military dictatorship, in Caracas on January 23, 2019. - "I swear to formally assume the national executive powers as acting president of Venezuela to end the usurpation, (install) a transitional government and hold free elections," said Guaido as thousands of supporters cheered. Moments earlier, the loyalist-dominated Supreme Court ordered a criminal investigation of the opposition-controlled legislature. (Photo by Federico PARRA / AFP) (Photo credit should read FEDERICO PARRA/AFP/Getty Images) AFP/Getty Venezuelans make art from banknotes in bid to give them value venezuela-currency-11.jpg People raise their hands during a mass opposition rally against President Nicolas Maduro in which Venezuela's National Assembly head Juan Guaido (out of frame) declared himself the country's "acting president", on the anniversary of a 1958 uprising that overthrew a military dictatorship, in Caracas on January 23, 2019. - "I swear to formally assume the national executive powers as acting president of Venezuela to end the usurpation, (install) a transitional government and hold free elections," said Guaido as thousands of supporters cheered. Moments earlier, the loyalist-dominated Supreme Court ordered a criminal investigation of the opposition-controlled legislature. (Photo by Federico PARRA / AFP) (Photo credit should read FEDERICO PARRA/AFP/Getty Images) AFP/Getty

Mr Guaido – who last month declared himself interim president and was recognised by the US, UK and other nations – has called on thousands of ordinary Venezuelans to assemble there on Saturday to help bring it across.

“Through this call for humanitarian aid, the population will benefit from the arrival of these goods to the Venezuelan border,” opposition politician Edgar Zambrano told the news agency.

The opposition leader appears to be using the weekend’s plan to bring in aid in a test of Mr Maduro’s will, according to some observers.

“The whole “humanitarian aid” operation is just a public relations stunt, and has been denounced by real humanitarian aid organizations including the International Red Cross and the United Nations,” Mark Weisbrot, a regional expert and co-director of the Centre for Economic and Policy Research, a think tank in Washington DC, told The Independent. “And we know that Trump himself has been looking for a war in Venezuela, for which this confrontation could serve as pretext.”

Trump says Venezuela's military will 'lose everything they have' if they continue to support Maduro

The Venezuelan president has said he is happy to accept aid shipments overseen by the UN, but believes the aid Mr Guaido seeks to bring in is part of an attempt to overthrow his government – something both Mr Guaido and Donald Trump have stated is their desire.

Long-time observers of Latin America have pointed out that the US has previous used aid shipments to smuggle in weapons to groups fighting the elected governments of several nations.

Meanwhile, UN agencies have been stepping up their work inside Venezuela while urging that the distribution of aid not become politicised. On Tuesday, Brazil, whose recently elected right-wing president Jair Bolsonaro is among those that recognise Mr Guaidó as Venezuela’s “legitimate leader”, said it would work to distribute the aid.

Brazil’s foreign ministry said in a statement the aid will be placed in Boa Vista and the border town of Pacaraima to be collected by what it described as “the government of acting President Juan Guaidó”.

“Brazil is thus joining this important international initiative to support the Guaidó government and the people of Venezuela,” the statement said.

A US envoy is heading to Colombia as part of a mission to send food and other emergency supplies into Venezuela. The State Department announced late Thursday that special representative Elliott Abrams will lead a US government delegation transporting humanitarian supplies.

Jens Laerke, a spokesman for the UN Office for the Coordination of Humanitarian Affairs, told Voice of America the UN was closely monitoring the situation on the border.