The Nicaraguan government’s expulsion of the apostolic nuncio, Archbishop Waldemar Sommertag, is “grave and unjustified,” the Vatican said.

The Nicaraguan government has offered no official explanation for barring the Vatican’s diplomatic representative from the country, but tensions between the Church and the government of strongman Daniel Ortega have been rising steadily.

Last year a group of opposition leaders asked Archbishop Sommertag to intervene with Ortega on behalf of political prisoners. The archbishop told AP that that he had always sought to help “the most vulnerable, among those detainees of all categories, including political.”