Pope Paul today promoted Czechoslovakia's leading Roman Catholic prelate to primate of his country in a move that marked improved relations between the Vatican and the Czechoslovak Communist rulers.

Frantisek Tomasek, named a Cardinal last year, now becomes Archibishop of Prague. He had been apostolic administrator -- generally an interim position -- for 12 years.

Czechoslovakia has been without a primate since Archbishop Josef Beran, one of thousands of Roman Catholics imprisoned in the early 1950's, died in 1969 while in exile in Rome.

A Vatican announcement said Cardinal Tomasek's appointment was part of the Pope's plans to "normalize relations with Czechoslovakia." It follows private talks between Vatican officials and a special Czechoslovak government mission here in September.

The church says that 10 million of the 15 million Czechoslovaks are Roman Catholics. Last year Pope Paul called for special prayers for those "who live in tribulation, suffering and ranger in Czechoslovakia." With Tomasek's appointment, 9 of the 13 dioceses in Czechoslovakia remain without regular bishops, because of past problems between the Vatican and Prague's leadership.

The Vatican also announced a number of important territorial changes in the Czechoslovak church which Vatican sources said could only have been made with the approval of the Prague government.

The changes realigned ecclesiastical boundaries with national frontiers for the first time since World War II, transferring control of dozens of border parishes, formerly under the jurisdiction of dioceses in Poland and Romania, to the Czechoslovak church.