The embattled President of Venezuela, Nicolás Maduro, has ordered the closure of the border with Brazil in the midst of the controversy over foreign humanitarian aid.
The leftist leader went on TV to say he was also considering shutting the key border with Colombia to stop the opposition bringing in relief.
The President denied the existence of any crisis in the country and called the aid delivery plans a US-orchestrated show.
The opposition leader, Juan Guaidó, is leading a convoy from the capital, Caracas, to the Colombian border.
Later on Friday, a concert will be held on the Colombian side of the border to raise money for Venezuela. At the same time, Maduro’s government will hold its own event, reportedly just 300m (980ft) away.
Guaidó, head of the National Assembly, declared himself interim leader during anti-government protests last month and is recognised by dozens of countries, including the US and most Latin American nations.
He and his allies hope to collect food and medicine being gathered in neighbouring Brazil and Colombia on Saturday, in defiance of President Maduro.
Flanked by Venezuela’s defence minister and other top military commanders, Mr Maduro announced that the border with Brazil would be closed “completely and absolutely” until further notice on Thursday night.
The crossing usually closes at night and would normally open at 08:00 local time (12:00 GMT).
After the announcement, many Venezuelans rushed to the Brazilian city of Pacaraima to stock up on supplies.