Venezuela’s government has said that Brazil can no longer represent Argentina’s diplomatic interests in the country, putting several anti-government opponents holed up for months in the Argentine ambassador’s residence seeking asylum at risk, as reports emerge that the embassy has been surrounded by security forces.

Venezuela’s foreign ministry said in a statement that it had notified Brazil of its decision, which will take effect immediately. It said it was forced to take action based on what it called evidence – which it hasn’t shared – that those who sought refuge in Argentina’s diplomatic mission were conspiring to carry out “terrorist” acts.

Brazil said that it had received the communication “with surprise” and Argentina said shortly afterwards that it rejected the “unilateral” decision by Venezuela. Both countries urged the government of Nicolas Maduro to respect the Vienna convention on diplomatic relations.

“Any attempt to invade or kidnap asylum seekers who remain in our official residence will be harshly condemned by the international community,” Argentina said in a statement. “Actions like these reinforce the conviction that in Maduro’s Venezuela, the fundamental human rights are not respected.“

In its statement, Brazil insisted that it would remain in custody and defence of Argentine interests until Argentina indicates another state acceptable to Venezuela to do so.

On Friday night, some opposition members in the Argentine residence reported on social media that the building was under surveillance and had no electricity. They posted videos showing men dressed in black and patrols from the government intelligence agency.

In March, six people sought asylum in the Argentine embassy in Caracas after a prosecutor ordered their arrest on charges including conspiracy. Opposition leader Maria Corina Machado has denied the allegations against her collaborators.

Saturday’s move from Venezuela is the latest burst of friction between the countries. Argentina’s president has been among those leading the charge against Maduro over alleged attempts to steal July’s presidential election. Electoral authorities pronounced Maduro the winner despite strong evidence collected at the ballot boxes by the opposition that it prevailed by a more than 2-to-1 margin. Since the election, thousands have been arrested in a brutal crackdown.

Magalli Meda, the former campaign chief Machado, was among a half-dozen government opponents who fled to the Argentina ambassador’s residence after Maduro’s chief prosecutor issued an order for her arrest in March for allegedly propagating destabilising political violence.

In retaliation, Maduro broke off diplomatic relations with Argentine president Javier Milei’s right-wing government, which tapped neighbour Brazil to represent its interests and safeguard the asylum seekers.

Meda has taken to social media to denounce what she fears is an impending raid to arrest her and the other government opponents by Venezuelan security forces.

Reuters and the Associated Press contributed to this report