Fewer independent candidates than before are standing in Sunday's election for the 500-seat National Assembly, which is held every five years and usually after the ruling Communist Party holds its congress to select a new leadership.

Despite increasing openness to social change in the Southeast Asia nation and a plethora of free trade deals, the Communist Party - one of the last ruling communist parties in the world - retains tight control over Vietnam and its media, and tolerates little dissent.

The nearly 69.2 million registered voters will also vote for members of the people's councils at provincial and district levels.

More than 90 per cent of candidates for the National Assembly are members of the Communist Party, which also essentially vets independent candidates.

The number of candidates who are not party members fell this year to 74 from the 97 in the previous elections in 2016. Local media say the number of assembly deputies who were not party members halved in the past three elections.

The election is taking place as Vietnam battles a new COVID-19 outbreak that is spreading rapidly, infecting 2066 people since it emerged in late April.

In Hanoi's Long Bien district, about 30 voters were seen queuing by a voting booth waiting for their turn, all wearing masks.

Before queuing, the voters had their temperature taken at a nearby table where free masks and hand sanitiser were offered, with a loudspeaker broadcasting advice to keep a safe distance.

National Assembly chairman Vuong Dinh Hue said the vote was the first "amid the most dangerous coronavirus outbreak that has spread to nearly half of the number of provinces, with many of them under lockdown".

Election results are typically announced after about two weeks.

Australian Associated Press