The government of Chile has demanded that Venezuela "immediately" disclose the location of a journalist who was detained earlier this month.
In return Venezuela accused Chile of "inadmissible interventionism" and a "lack of diplomatic circumspection".
Braulio Jatar was taken into custody on 3 September after publishing videos of a protest against Venezuelan President Nicolas Maduro.
Mr Jatar was born in Chile and also has Venezuelan nationality.
He is an open supporter of the opposition and runs a news website on Margarita island in Venezuela.
The Committee to Protect Journalists, a New York-based pressure group, called on Venezuela to "allow all journalists to report freely".
On Monday. Brazil's foreign minister also criticised the Venezuelan government's actions, saying the country had seen an increase in what he called "arbitrary detentions".
Jose Serra told a local newspaper such detentions "make it even more difficult to have the dialogue between government and opposition that is indispensable for overcoming the dramatic political, economic, social and humanitarian crisis that is affecting Venezuela".
'Bowing to pressure'
At the start of September, Mr Jatar released videos of a protest when island residents jeered the president.
Protests have been a regular occurrence in Venezuela as the opposition calls for President Maduro to be removed from power. They blame him for the country's economic crisis and accuse the electoral commission of delaying a referendum that could shorten his rule.
President Maduro accuses the opposition of trying to stage a coup.
Mr Jatar was arrested with about 30 other people on Margarita island. The others have since been released but Mr Jatar is still in detention and his family believe he is not on the island any more.
Some reports said the authorities claimed he had tens of thousands of dollars in cash, which was to be used to attack an international summit starting on Margarita island on Tuesday.
Venezuelan prosecutors have not commented on the detention but the foreign ministry said he was suspected of extortion and fraud.
Chile demanded at the weekend that Venezuela make the journalist's whereabouts known.
The Venezuelan government said it "rejected" the demand and accused the Chilean foreign minister of "bowing to pressure from the most reactionary sections of the bourgeoisie" who still support General Pinochet, the country's former right-wing dictator.
Chile's response was to say that "the promotion and defence of human rights do not have borders" and Mr Jatar had not had access to his lawyer in a week.