The number of childbirths in South Korea sank at the fastest clip in nearly three years in July amid a continued low birth rate and late marriage trend, government data showed Wednesday.

About 33,900 babies were born in July, down 7.4 percent, or 2,700, from 36,600 a year earlier, marking the steepest monthly drop since November 2013, when it posted a 12.3 percent on-year plunge, according to the data from Statistics Korea.

The number of marriages fell 10.2 percent on-year to a 10-month low of 21,200 in July, while 8,700 couples divorced, marking an 8.4 percent drop over the cited period.

The July number of deaths climbed 2.8 percent to 22,100 from a year ago, the report showed.

Coupled with rapid aging, low birth rate has been regarded as one of the biggest threats to the South Korean economy.

The chronically low birth rate and aging population are feared to reduce the workforce and drive up welfare costs, undermining the growth potential of Asia's fourth-largest economy.

The country's fertility rate, or the average number of babies that a woman is projected to have during her lifetime, hit a record low of 1.08 in 2005 and has hovered around 1.2 in recent years, despite the government's constant efforts to encourage people to have more children.

The latest census data showed that people aged over 65 years made up 13.2 percent of all its citizens of 51 million last year.

Nations become an "aged society" if the percentage reaches 14 percent. (Yonhap)