A controversial South Korean marriage ban which prohibits couples of the same surname from marrying is to remain in place, authorities have ruled.

The 691-year-old ban has had an enormous impact on South Korea where 47 million people share only a few dozen surnames.

Arguing that it no longer reflected modern society, the government had asked the country's National Assembly to repeal the law.

The law banning same-surname marriages dates back to the year 1308, when inbreeding was a concern because families lived in the same isolated villages for generations.

The government drafted a bill to lift the ban after the Constitutional Court ruled in 1997 that it violated the right to pursue happiness.

However, a committee set up to look into the law has ruled that a repeal would be premature.

Confucian groups have welcomed the decision, since the restriction conforms to their beliefs that male descendants are part of the same family, regardless of the generations separating them.

'Outmoded and unrealistic'

The move has angered human rights groups who insist the ban is outmoded and unrealistic.

In South Korean society, co-habiting without marrying is considered shameful.

But according to estimates, as many as 60,000 couples are believed to be living together outside marriage because they share the same clan names - even though there is no evidence they share the same blood lines.