By Bill Hayton
BBC News, Hanoi
A delegation from the Vatican has arrived in Vietnam for the latest round of negotiations on establishing diplomatic ties between the two sides.
The Pope and the Vietnamese Prime Minister met in January
The visit comes shortly after the detention of a Catholic priest as well as allegation of abuses of believers by local officials in the country.
Vietnam's government wants to establish relations quickly but the Vatican wants to see several issues resolved first.
This is the 15th round of talks between Vietnam and the Vatican.
The two sides have made considerable progress, and Vietnam's prime minister met Pope Benedict in Rome in January.
But the Vatican - whose delegation is being led by the Holy See's Undersecretary of State for Relations with States, Monsignor Pietro Parolin - remains concerned about a number of issues.
Last month, Father Nguyen Van Ly, a Catholic priest and democracy activist, was taken from his home in the Bishop's Palace in the central city of Hue by police and placed under house arrest 20kms (12 miles) outside the city.
A Vatican news agency has also alleged mistreatment of Catholics by, among others, local authorities in the north west of Vietnam.
The Vatican wants the government to return church property confiscated decades ago, and also to be allowed to provide more education and welfare services.
This is something the government is considering as it tries to manage some of the problems caused by Vietnam's rapid economic development.
The government keeps the Catholic Church under tight control - for example, it must approve the appointment of every priest.
This is a legacy of a time when the communist authorities saw the church as an agent of colonialism.
But times have changed and now it sees the church as a potential ally against social problems and even as a force for national unity.