Relations between the Vatican and communist leaders of Vietnam are seen as improving after Pope Francis included in the latest batch of cardinals the appointment of Hanoi Archbishop Pierre Nguyen Van Nhon.

Nhon, 76, said his red hat represents the challenging task ahead of him, as the Holy See and Hanoi have sought to re-establish diplomatic ties, a report by Radio Free Asia reported.

The archbishop admitted, however, that the Church leadership has a lot on its plate for the roughly six million followers in Vietnam.

There religious activity continues to be under State control despite government claims of religious freedom.

Christians make up the second largest religious group in the country, after Buddhists who comprise the majority of Vietnam's 92.5 million population.

The Vatican and Hanoi have not had formal diplomatic relations since the communist government took power in 1975. Dialogue between the parties resumed in 2007 with the establishment of a Joint Working Group.

"Based on visits exchanged between the two sides and especially the presence of ... the Vatican's representative in Hanoi, we can see there have been efforts to hold productive dialogue," said Nhon.

"Such dialogue requires patience and sincerity. I've seen obvious efforts from the Vatican, as well as from the government [of Vietnam]. The direction looks positive, but the path is still long and we need time," he continued.

Nhon observed that Catholics in Vietnam are generally optimistic about the efforts to improve religious freedom in the country. He said that some problems church followers encounter are usually isolated.

Nhon takes over from Cardinal John Baptist Pham Minh Man, who retired last year at the age of 80.

"The work has been there always and now I will have to do it better," said Nhon, who was ordained as a priest in 1967 and named Hanoi archbishop in 2010.