"The Holy See expressed its pleasure at the visit, a significant stage in the progress of bilateral relations with Vietnam," the Vatican said in a communique.

It added that the Vatican hoped "outstanding questions may be resolved as soon as possible."

Early this year a senior Vatican official held the first formal meetings with Vietnamese authorities in Hanoi to discuss diplomatic ties.

Bilateral relations "have made a lot of progress recently," said Vietnamese foreign affairs spokeswoman Nguyen Phuong Nga last week when announcing Triet's planned meeting with the pope.

Prime minister Nguyen Tan Dung made a historic visit to the Vatican in 2007, marking a major thaw in relations following a series of trips to Vietnam by Vatican delegations from 1969.

Among thorny issues is the question of Catholic land confiscated after the end of French colonial rule in the north in 1954 and by the communist regime after reunification in 1975.

In December 2007, Catholics began a series of demonstrations over seized land that led to occasional clashes with the police.

A Catholic priest, Nguyen Van Ly, was jailed for eight years in 2007 for spreading propaganda against the communist state.

The case drew condemnation from diplomats, Vietnam watchers and human rights groups, and in early July this year a bipartisan group of 37 US senators sent a letter to Triet calling for Ly's release. His sister has said he is in deteriorating health.

Vietnam, where religious activity remains under state control, in Vietnam. has Southeast Asia's largest Roman Catholic community after the Philippines -- about six million in a population of 86 million

Triet's Vatican stop is part of a European tour to include Italy, Spain and Slovakia.

Agence France Presse - December 14, 2009