LA PAZ (Reuters) – The European Union said on Tuesday it was “deeply concerned” about Bolivia’s expulsion of Spanish officials caught up in an escalating diplomatic row between Mexico and the interim conservative administration in La Paz.

Bolivian stand-in President Jeanine Anez said Monday her administration had asked Mexican ambassador María Teresa Mercado and several Spanish officials to leave the country within 72 hours.

Anez said Bolivia expelled the Spanish diplomats because masked men posing a “security risk” had accompanied the officials on a visit to Mexico´s embassy in La Paz.

“Expelling diplomatic officials is an extreme and unfriendly measure that should be saved for grave situations,” the EU said in a statement.

The EU said it was “deeply concerned over the increasing diplomatic tension” and has demanded further explanation from the Anez government.

Spain’s foreign ministry responded to the expulsion of its officials with a tit-for-tat move, saying it would expel three Bolivian diplomatic staff.

The row began after Mexico admitted ousted Bolivian President Evo Morales as an exile following allegations he had rigged the country´s October presidential election. Morales is now in Argentina.

    Mexico’s embassy in Bolivia has given refuge to nine people, including Morales allies whom the Anez administration blames for stirring up violent protests and wants to put on trial.

Bolivia’s disputed October election sparked widespread, often violent demonstrations. Morales resigned last month in the face of growing civil and military pressure. Anez took over by default, and has made sharp policy shifts away from his socialist government, fraying ties with leftist allies in the region.

Morales claimed he was toppled in a right-wing “coup” and many of his allies have rallied behind him with the country headed for new elections in 2020.

Reporting by Monica Machicao and Daniel Ramos, writing by Dave Sherwood