SAO PAULO — A group of supporters of Venezuelan opposition leader Juan Guaidó seized the Venezuelan Embassy in Brasilia early Wednesday, claiming its employees defected and voluntarily let them.

But Freddy Meregote, the embassy chargé d’affaires representing the government of embattled President Nicolás Maduro, said that the staff remains loyal to Maduro and that Guaidó supporters forced their way in.

“We need help and immediate activation of all social movements and political parties,” Meregote said in audio messages sent to leaders in Brazil’s National Congress.

Outside the embassy, a small crowd of Maduro supporters and members of Brazil’s leftist Workers’ Party protested.

The confrontation occurred as the leaders of Brazil, China, Russia, India and South Africa arrived in Brasilia for a summit to discuss the instability in Venezuela, among other issues.

Brazilian police surrounded the embassy but did not enter. The standoff ended shortly after 5 p.m., as a group of at least 14 Guaidó supporters left the embassy under escort by police and members of the Brazilian Foreign Ministry. They had occupied the facility for more than 12 hours.

The socialist Maduro, successor of the late Venezuelan president Hugo Chávez, claimed victory last year in elections widely viewed as fraudulent. Venezuela’s opposition-controlled National Assembly declared Maduro a usurper and installed Guaidó as the country’s rightful leader until free and fair elections can be held.

The United States, Brazil and some 50 other countries recognize Guaidó as Venezuela’s president; China, Russia and others back Maduro.

Venezuelan Foreign Minister Jorge Arreaza denounced the “assault committed by violent groups” on its diplomatic mission “before the passive attitude of the Brazilian police authorities in inattention to their obligations.” In a statement, Arreaza demanded that Brazil “immediately take the necessary measures” to remove the “aggressors.”

The Brazilian government said President Jair Bolsonaro had no advance notice of the action by the Guaidó supporters.

“As always, there are unscrupulous and lightweight individuals who want to take advantage of events to create disorder and instability,” the institutional security office of the presidency said in a statement. “The president of the republic was never aware and much less encouraged the invasion of the Venezuelan Embassy.”

The office said local and national security forces were “ensuring that the situation is resolved peacefully and that there is a return to normalcy.”

Guaidó appointed María Teresa Belandria as his ambassador to Brazil in February, and she was recognized by Bolsonaro’s government in June. But she had not taken over the country’s official embassy, which is still staffed with Maduro loyalists. On Wednesday morning, she urged that staff to join their cause.

“We value the recognition of the legitimate government of President Guaidó and ask that all officials in the embassy and in the seven Venezuelan consulates adopt this same attitude and join their colleagues to work for all Venezuelans residing in Brazil,” Belandria said in a statement.

Bolsonaro’s son, lawmaker Eduardo Bolsonaro, tweeted his support for the occupation. He said Belandria, whom Brazil has recognized as ambassador, should be seated at the embassy.

“It seems to me that what is being done is right and just,” wrote the younger Bolsonaro, a member of the Chamber of Deputies.

Paulo Pimenta, head of the Workers’ Party in Brazil’s lower house, called the attack a coordinated effort between a militia and the Brazilian government.

“These men are uninformed and are clearly not representatives of the people or of the diplomatic corps,” he said in a video outside the embassy posted on Twitter.

Guaidó’s supporters took over the Venezuelan Embassy in Washington in April. The Maduro government retains control of the Venezuelan mission at the United Nations in New York.