The Venezuelan government has announced it will expel German ambassador Daniel Kriener.
A government statement declared Ambassador Kriener “persona non grata” and accused him of “recurrent acts of interference in internal affairs”.
Mr Kriener was among a group of diplomats who helped opposition leader Juan Guaidó return to Venezuela on Monday by meeting him at the airport.
Mr Guaidó had defied a travel ban and was widely expected to be arrested.
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But when he flew into Caracas’s main airport on Monday, he was let through immigration and a group of diplomats welcomed him and then escorted him out of the airport building.
Earlier, officials from the US, the EU and a number of Latin American countries had warned the Venezuelan government not to arrest or harm Mr Guaidó.
Mr Kriener has been given 48 hours to leave Venezuela, German broadcaster Tagesschau reports.
Diplomats from Argentina, Brazil, Canada, Chile, Ecuador, France, The Netherlands, Portugal, Romania, Spain and the US were at Simón Bolivar airport to receive Mr Guaidó on Monday but so far only Mr Kriener has been declared persona non grata over this incident.
Mr Guaidó, who leads the opposition-controlled National Assembly, declared himself interim president on 23 January and has been at loggerheads with President Nicolás Maduro ever since.
He has been recognised as interim president by more than 50 countries but Mr Maduro retains the support of his close allies Russia, Cuba and China among others.
Mr Maduro accuses Mr Guaidó of trying to mount a coup against him with the help of “US imperialists”. The government-dominated Supreme Court imposed a travel ban on the 35-year-old opposition politician.
It was widely expected that Mr Guaidó would be arrested after he defied the travel ban to go on a tour of Latin American countries to lobby for international support.
Before Mr Guaidó’s arrival, Ambassador Kriener had said he and other diplomats wanted “to help and support a safe return” for the opposition leader.
The German embassy in Caracas later tweeted [in Spanish]: “Juan Guaidó’s return to Venezuela is a step towards a political and peaceful process to overcome the Venezuelan crisis.”
Venezuela’s foreign ministry said that it would not accept a foreign diplomat acting “in clear alignment with the conspiracy agenda of extremist sectors of the Venezuelan opposition”.
The Maduro government is becoming increasingly isolated as more and more countries blame it for the economic crisis which is crippling the oil-rich country and which has prompted more than three million people to leave Venezuela.