Bolivia's interim president, Jeanine Anez, announced Monday that the country will expel Mexico's ambassador and two Spanish diplomats, escalating a dispute over an alleged attempt to extract an ex-government aide.
"The constitutional government that I preside over has decided to declare persona non grata the ambassador of Mexico in Bolivia, Maria Teresa Mercado, the chargé d'affaires of Spain, Cristina Borreguero, and the [Spanish] consul, Alvaro Fernández," Anez said.
She accused the diplomats of having "seriously harmed the sovereignty and dignity of the people and the constitutional government of Bolivia" and gave them 72 hours to depart.
Mexico's Foreign Ministry denounced the "political" decision and said it had instructed Mercado to return home.
The announcement by Bolivia came after the country accused Spanish Embassy staff of trying to infiltrate the Mexican mission in La Paz with a group of masked men to extract a wanted former aide of ex-president Evo Morales.
Morales – who resigned in November after weeks of protests over his controversial re-election – stands accused of sedition and terrorism and is living in exile in Argentina.
The Mexican Embassy has become the centre of a diplomatic row after it sheltered nine or more officials from Morales' former government.
Both Spain and Mexico said the incident occurred on Friday when Borreguero paid a brief visit to Mexico's ambassador.
But Madrid issued a strongly worded denial over the alleged attempt to extract the former Morales aide.
"The ministry wishes to clarify that the charge d'affaires was purely making a courtesy visit and vehemently denies there was any aim to facilitate the exit of people holed up inside the building," Spain's foreign ministry previously said.
Mexico's Foreign Ministry has said the incident occurred as Borreguero and Fernandez wrapped up a meeting with the ambassador.
But their official vehicles never turned up, and neither of them was able to reach their drivers or their security detail, a ministry statement said.
"On hearing shouting, Ambassador Mercado invited the two visitors to re-enter the residence. At that point, the Spanish diplomats were informed that their vehicles had been stopped from entering."
The Spaniards were advised to leave the embassy on foot but refused to do so without a security detail. Eventually, a Bolivian ministry car was sent to pick them up.
The presence of former top Bolivian officials inside the embassy has provoked a number of tense exchanges between La Paz and Mexico City.
Bolivia has warned that Mexico will face a "very serious problem" if its embassy refuses to hand over wanted officials, while Mexico has accused La Paz of "harassment and intimidation" for deploying multiple police and intelligence officers outside the premises.