A Nicaraguan presidential decree affecting the Holy See's ambassador in the Central American country appears to be retaliation for comments made by the local Church leadership criticizing the government's slide away from democracy, diplomats said on Friday.

President Daniel Ortega's decree this week stripped the Vatican's ambassador in Managua, Archbishop Waldemar Stanislaw Sommertag, of his title and role as dean of the diplomatic corps.

In many countries of Catholic tradition, the dean's position is held automatically by the Vatican envoy, known as a nuncio, regardless of how long he has been in the country.

Sommertag, a 53-year-old Pole who has held the position since 2018, has openly supported the local Church in its position defending democracy in the country.

The official Nicaraguan Gazette said the change revoking a previous agreement with the Vatican was made to comply with an article of the Vienna Convention of 1961 that Managua said calls for equal standing in the diplomatic corps.

Rome-based diplomats, a Vatican source and a professor of diplomatic law said, however, that the convention did allow for an informal hierarchy in a diplomatic corps and that the government action appeared to be an excuse.

Speaking on the condition of anonymity, they said the move appeared to be tied to the Church's stand in defence of democracy in recent years and particularly in the run-up to the recent elections.

"The timing of this is clear, coming almost two weeks after the elections. It is a shot across the bow of the Church, it seems to be a warning and a punishment," one diplomat said.

The government could not be immediately reached for comment.

Ortega, a Cold War-era former Marxist guerrilla leader who has held office since 2007, clinched a fourth consecutive term earlier this month after jailing political rivals ahead of elections that were widely condemned as not being free.

In the run-up to the elections, Nicaragua's Catholic bishops conference issued a statement that said the country was lacking "the basic and indispensable conditions in order to hold free, fair and transparent elections."

Before the election, the archdiocese of Managua issued a statement denouncing what it called the systematic violation of political and constitutional rights as well as "threats to the Catholic Church (and) offences against its priests and bishops."