Vietnam's economic hub Ho Chi Minh City began a two-week lockdown Friday in the hope to contain the country's worst Covid-19 virus outbreak.

The city of nine million had previously been subjected to travel restrictions for a month but infection rates were steadily rising -- with more than 9,400 cases registered.

Before the outbreak kicked off in late April, Vietnam had recorded fewer than 3,000 cases across the entire country.

Vietnamese authorities are not using the term lockdown but are calling the measures "social isolation orders".

Ho Chi Minh City residents are now barred from gathering in groups larger than pairs in public, and people are only allowed to leave home to buy food, medicine and in case of emergencies.

Police have set up check-points at city borders and only those with negative test results can get in.

Airlines can carry a maximum of 1,700 passengers to the capital Hanoi per day, aviation authorities said, while trains between Vietnam's two major destinations have been suspended.

"Our busy city has become extremely quiet," Tran Phuong, a Saigonese resident told AFP.

"I am anxious that these strict measures cannot help because the virus is now deep across the community."

Vietnam had once been hailed as a model for virus containment as a result of extensive contact tracing and strict quarantine rules.

Ho Chi Minh City residents are now barred from gathering in groups larger than pairs in public Ho Chi Minh City residents are now barred from gathering in groups larger than pairs in public Photo: AFP / Huu Khoa

All close contacts of virus patients have been put under state-controlled quarantine facilities.

Ho Chi Minh City was the first to adjust the strict policy, allowing close contacts to home quarantine because state-run isolation centres are overloaded.

Earlier state media reported more than 80 inmates and guards had tested positive at the city's Chi Hoa jail.

Gunshots rang out from inside the prison Tuesday, but it remains unclear what had happened.

Vietnam is juggling its desire to contain the virus with its economic growth goals.

The country has been among the best performing economies in Asia, reporting strong growth of 6.61 percent in the second quarter.

"The lockdown... is too hard. It will severely affect people. Our business has been suspended, so no income. Our life has been quite difficult," motorbike parts trader Nguyen Thi My Dung told AFP.

Vietnam, which has a population of close to 100 million, has administered almost four million doses of Covid-19 vaccines.

Authorities want to reach herd immunity by the end of the year or early 2022.

Vietnam is developing its own vaccines and has ordered millions of doses from abroad.