Image copyright news1 Image caption A South Korean man (centre) was arrested after he was allegedly filmed beating his wife in a highly distressing attack

A horrific video purportedly showing a South Korean man beating his Vietnamese wife in front of a child has ignited outrage over the abuse of foreign women in the country.

The 36-year-old man was arrested on Saturday, and the woman involved has been moved to a women's shelter with her young son.

Warning: this article contains descriptions of violence

The video has shed light on the vulnerability of foreign women who marry South Koreans - sometimes finding themselves at the mercy of abusive spouses who rarely face the force of the law.

Last year, a survey of 920 foreign wives in South Korea by the National Human Rights Commission found that 42% had suffered domestic violence, and 68% had experienced unwanted sexual advances.

'You are not in Vietnam'

The footage, posted on Facebook but since taken down, shows the man slapping and kicking the woman, and repeatedly punching her in the head and stomach while she cowers.

"Didn't I tell you that you are not in Vietnam?" he shouts.

Local media said the victim had managed to film the assault by hiding her mobile phone in a nappy bag at her home in Yeongam, South Jeolla province.

She suffered broken ribs in the attack. A two-year-old boy, apparently their son, is seen in the video crying by the woman's side.

At their husbands' mercy

Analysis by Hyung Eun Kim, BBC Korean Service

Although a high number of foreign wives experience domestic abuse, few report it to the authorities. And advocacy groups say there are clear reasons why.

"In the worst-case scenario, South Korean husbands and their families deliberately refrain from helping their migrant wives obtain citizenship or visa status," Kang Hye-sook, a director of the Woman Migrants Human Rights Center in Daegu, told the BBC Korean Service.

So for a foreign wife to report abuse and upset her husband is tantamount to giving up her "Korea Dream". It makes her already-vulnerable status even weaker. If she happens to have kids, the move could also mean never seeing them again.

There is also a tendency in South Korea to treat domestic violence as a "family matter". Of reported domestic violence cases for the past five years, only 13% saw arrests, 8.5% resulted in an indictment, and just 0.9% drew an actual prison sentence.

Last year, a series of women were murdered after suffering lengthy (and reported) abuse from their husbands, shocking South Korea. After one murder, the daughter of the victim posted an online petition, seeking capital punishment for the father who had stabbed her mother.

She said her father had openly declared: "I can kill her and be a free man just after a six-month [jail] sentence."

In November 2018, the gender equality ministry, justice ministry and police responded with a series of stricter measures against domestic violence, including tougher penalties for people who violate restraining orders. But many of the measures need to pass parliament's legislation process - and that is yet to happen.

What's driving international marriages?

In South Korea, both men and women face social pressure to get married. But it's not always easy - especially in the countryside, where many women leave to find jobs in the cities.

In the 1990s, that trend prompted a boom in men marrying foreign women, which has since spread to urban areas.

Some local governments, keen to raise flagging population rates, even provide subsidies to Korean men who bring home a bride from overseas.

Vietnamese women make up the biggest percentage of foreign wives in South Korea, at 28%, 2017 figures from Statistics Korea show.

South Korea's rapid economic development has made it an enticing prospect. And in exchange for a higher standard of living, some women in their early- or mid-20s are prepared to marry near-strangers who are - on average - around 18 years their senior.

They may have friends who have moved to South Korea and report being happily married. And some are enticed by the vision of Seoul presented by Korean films and TV shows, which are popular across Vietnam.

Such marriages used to be arranged through specialist international matchmakers, but the use of these agencies has fallen in recent years.

Image copyright HOANG DINH NAM Image caption Matchmakers often seek to promote Vietnamese women by saying they were raised to obey their husbands. (File picture - a visa queue in Ho Chi Minh city)

Matchmaking companies will often pander to South Korea's patriarchal traditions by saying Vietnamese women are raised with "Confucian values" (a philosophy also rooted in Korean culture) - meaning they are obedient to men and the elderly, and will serve their husbands and parents-in-law well.

But there have been several high-profile cases of domestic violence against them.

In 2010, a 20-year-old Vietnamese bride named Thach Thi Hoang Ngoc was beaten and stabbed to death by her 47-year-old husband eight days after arriving in Korea. Her husband, it transpired, had a history of schizophrenia that had not been disclosed to his wife.

In a radio address to the nation, South Korea's then-President Lee Myung-bak offered his "deepest sympathy to her family". He said her last words to her father had been: "I will live happily."

The mistreatment of migrant wives has also been a running topic in bilateral diplomacy.

In 2007, the then president of Vietnam formally asked the South Korean ambassador in Vietnam to help Korean men "treat Vietnamese wives well".

And last year, a South Korean congressman was lambasted by women's rights activists after telling a Vietnamese counterpart that "South Korean men prefer Vietnamese woman".