Global burger behemoth McDonald's opened its first branch on Saturday in the historic heart of Hanoi, a city renowned for its traditional -- and cheap -- Vietnamese staples beloved by food-obsessed locals.

Hungry customers lined up for Big Macs and Chicken McNuggets at the Vietnamese capital's first location overlooking the tree-lined Hoan Kiem lake, in a city that draws millions of tourists annually to see French-era colonial buildings and sample street-food favourites like pho noodle soup and banh mi sandwiches.

The restaurant is the first outside of the southern commercial hub Ho Chi Minh City, where 16 branches have opened since McDonald's first came to Vietnam in 2014 to much fanfare, especially among the rapidly-growing middle class and American-obsessed youth.

The global fast food chain received a similarly warm welcome in Hanoi on Saturday, as hungry diners crammed into the two-storey eatery for a first taste of the Golden Arches.

For 84-year-old Tran Dinh Luyen, who fought against the U.S. in the American war in Vietnam, the restaurant was a sign of warming ties with a former enemy.

"I am happy that McDonald's has opened a restaurant in Hanoi. It's a very famous American brand, so it shows how far U.S.-Vietnam relations have come," he told AFP after mowing down on a Big Mac with his daughter and granddaughter.

But not everyone agreed.

"It's a rip-off... this fast food is for kids only, it's not good at all," 90-year-old Ta Xuan Huong said, espousing his love for traditional cuisine.

Some curious tourists stopped to see what all the fuss was about, perplexed that a brand ubiquitous in the West would draw so much attention.

"It's kind of random to see McDonald's opening... it's an interesting cultural experience to see how important it is that the store is opening here," American Dan Moore told AFP, after his wife remarked she might not have expected to find one of the most salient symbols of capitalism in this country.

The fast food industry in Vietnam has seen double-digit growth annually for the past five years. Photo: AFP

Sizzling market

Vietnam has seen dizzying economic growth in recent years as it has opened its doors to foreign investment, which has included an influx of Western chains like Starbucks, KFC and Burger King.

Growth in the fast food sector has been buoyed by rapidly rising incomes -- annual per capita income has more than doubled in the past decade to about $2,100 today -- especially among under-30s, who make up half of Vietnam's population of 93 million people.

The man who brought the chain to the country, Henry Nguyen -- a Vietnamese American who once flipped burgers for McDonald's in the United States where he grew up -- said the Vietnamese market has great potential.

"Vietnam is on a growth trajectory that we believe that in five years, 10 years, 20 years, is going to be a fantastic market and to be able to try to capture that opportunity, you need to be able to build from today," said Nguyen.

The fast food industry in Vietnam has seen double-digit growth annually for the past five years, and the country has the highest 2017 growth in Asia-Pacific for fast food chains, according to market research firm Euromonitor International.

Though meals can cost as much as three times the local fare, customers are still showing strong appetite.

"Young people like to hang out in fast food restaurants as they are seen as a cool and nice place ... and these customers also like the taste of the food," Euromonitor analyst Samuel Huynh told AFP.