Venezuela's president Nicolas Maduro announced on Saturday that he would break relations with Colombia and expel employees from the country's Colombian embassy.
"Patience is exhausted, I can't bear it anymore, we can't keep putting up with Colombian territory being used for attacks against Venezuela. For that reason, I have decided to break all political and diplomatic relations with Colombia's fascist government," Maduro said in a speech.
He added that the Colombia ambassador and consular staff would have to leave Venezuela within 24 hours.
Meanwhile, on the border with Brazil, two people were killed on Saturday in the Venezuelan town of Santa Elena de Uairen in clashes with security forces over the opposition's plan to bring in aid from nearby Brazil, Reuters reported citing a doctor at the hospital where they were taken.
Maduro's announcement to break diplomatic relations with Colombia followed tensions at the Venezuelan-Colombian border as humanitarian aid for Venezuela was being unloaded at the Simon Bolivar bridge on Colombia's side of the border. The aid would be transported by a human chain across the frontier, Colombia's migration agency said.
President Maduro has ordered Venezuela's armed forces to block the aid from crossing into the country, as the embattled president denies that Venezuela suffers from widespread shortages of food and medicine.
A truck carrying aid along the Colombian border went up in flames shortly after Maduro's announcement, as crowds of volunteers started to take food and medicine off a second truck, local media reported. At least 42 people were injured in clashes on the Venezuelan-Colombian border.
After Maduro formally broke off relations with Bogota, Colombia's foreign minister said that Maduro is responsible for the safety of Colombian diplomats in Venezuela: "Colombia holds the usurper Maduro responsible for any aggression or violation of the rights of Colombian officials in Venezuela," Foreign Minister Carlos Holmes Trujillo said.
In a statement on Sunday, the EU condemned the "escalation of tensions" stemming from "the refusal of the regime to recognise the humanitarian emergency" and said it was ready to commit to more humanitarian aid for Venezuela.
"We strongly call on law enforcement and security bodies to show restraint, avoid use of force and allow for the entry of aid. We repudiate the use of irregular armed groups to intimidate civilians and lawmakers who have mobilised to distribute assistance", the EU's High Representative for Foreign Affairs and Security Policy, Federica Mogherini, said.
Juan Guaido, the self-proclaimed interim president who is recognised by most Western nations as Venezuela's legitimate head of state, defied court orders not to leave Venezuela by arriving on Friday in the Colombian border city of Cucuta, where aid from the U.S. and Colombian governments is stockpiled in warehouses.
"Today the obstacles that the dictatorship created will tomorrow be rivers of unity of peace," Guaido, the 35-year-old head of the opposition-run Congress, said in a news conference on Friday in Cucuta, where he was received by Colombian President Ivan Duque.
Vice President Delcy Rodriguez said in a tweet late on Friday that Venezuela's government shut the Tachira border that connects it with Cucuta temporarily "due to a series of illegal threats" by Colombia.
One of three bridges linking Cucuta to Venezuela has been blocked with shipping containers, while the other two have been shuttered to vehicle traffic for years.
Maduro has also shut the Brazilian border and the maritime border with nearby Dutch Caribbean islands.
Maduro blames the country's dire situation on U.S. sanctions that have blocked the country from obtaining financing and have hobbled the OPEC nation's oil industry. Rodriguez says the aid is poisoned.
Concerns about the potential for violence flared on Friday when the Venezuelan army opened fire in an village near the Brazilian border after indigenous leaders attempted to prevent them from advancing, killing a woman and her husband.
"I don't plan to leave my house over the weekend, especially after what happened near Brazil," said Paulina Sanchez, a 68-year-old grandmother who lives just 300 meters (yards) from the Francisco de Paula Santander bridge, one of the crossings through which aid may pass, told Reuters. "This could turn into a powder keg."
Nearly 200,000 people attended a festive benefit concert in Cucuta on Friday featuring Latin pop stars, including Luis Fonsi of "Despacito" fame, many of whom called on Maduro to step down.
A rival concert held by the ruling Socialist Party on the Venezuelan side was sparsely attended.
Guaido in January invoked articles of the constitution to assume interim presidency and denounced Maduro as a usurper, arguing his 2018 re-election was illegitimate.