In Ho Chi Minh City’s Go Vap District, Hanh, owner of a hotpot restaurant which serves alcohol, said last week revenues were down 30 percent. On some days the number of customers was 70 percent less than normal, she said.

"We have been offering a 10 percent discount to groups of four but it has not worked. Most of my customers now are those living within walking distance; those further away do not show up."

Phuc, business manager of the Biacraft beer chain, said revenues had fallen by 30-40 percent as the number of customers dropped from 200 a day to 130.

On Pham Van Dong Road in Thu Duc District, a popular spot for drinking, restaurants and eateries reported a 30-50 percent fall in the number of customers. Waiters stand on the street to hail customers, but to no avail.

Quy, manager of a beer club on the road, said the traffic police have been ubiquitous in the area since the beginning of the year, causing drinkers to go elsewhere.

Hanoi is seeing a similar trend.

Hoang Viet’s restaurant in Hanoi’s Cau Giay District saw the number of customers drop by half last week.

Consumption of beer and liquor was down, but customers drank more tea and non-alcoholic beverages, he said. Those who came to drink alcohol mostly came by taxi or ride-hailing cars, not by personal vehicles, he added.

The new Law on Preventing Alcohol's Harmful Effects, which took effect on January 1, imposes stiff penalties for drunk driving. Cyclists and electric bicycle riders face fines of VND400,000-600,000 ($17-26) for drunk driving.

Motorcyclists and car drivers can be fined VND6-8 million and VND30-40 million ($1,394-1,725), double the old levels, and everyone caught driving a vehicle under the influence could have their driving license suspended for 22-24 months.

Desperate, some restaurants are offering to drop customers off after they drink.

Tam, who owns a beer club in Hai Chau District, Da Nang, has hired two drivers to transport customers home. But the number of customers still downs. "Most would rather not drink."

Hung’s beer club in Thanh Hoa Town offers free motorbike and car rides home to people living within five kilometers. After the number of customers dropped by 20 percent, Hung has been publicizing this service on his Facebook page.

Doan Ba Ninh, manager of a restaurant in Hanoi’s Thanh Xuan District with 1,500 covers, offers to keep customers’ vehicles overnight. His employees will order ride-hailing services for customers who are too drunk to drive home. "But the number of customers is still down by around 30 percent."

Vietnam’s beer market growth is expected to be slower this year with the new law.

The country consumed some 4.6 billion liters of beer in 2019 after rising 10 percent from 2018, but growth could fall to 6-7 percent this year, top brokerage SSI Securities Corporation said in a note.