Vietnam's population is increasingly imbalanced between men and women, threatening to leave young males without female partners, the United Nations said Tuesday.
The country's national average sex ratio at birth is 110.6 males per 100 females, compared with a biologically standard figure of 105, the UN Population Fund (UNFPA) said.
A rapid increase in the proportion of boy births over the past five years "has caught worldwide attention and generated concern," said Bruce Campbell, the fund's Vietnam representative.
The trend's most likely cause is a parental tendency to have sex-selective abortions after learning that the foetus was a girl, the UNFPA report said.
Vietnam banned foetal sex selection in 2003, but the practice continues.
The distorted ratio will have an impact on the communist nation's young adults, "particularly the male capacity to find a female partner," the UNFPA said.
While other countries including China and India have experienced a rise in the number of male babies -- exceeding the ratio in Vietnam -- their increases have occurred over a much longer period, it added.
Neighbouring countries such as Cambodia, Thailand and Indonesia, which are demographically and socio-economically similar to Vietnam, have not experienced any significant rise in sex ratios at birth in recent decades, the report said.
In May last year Vietnam's Deputy Prime Minister Nguyen Thien Nhan said the gender imbalance would leave about three million men with difficulty finding wives by 2030, state-run Vietnam News Agency said.
Men in Vietnam have traditionally carried on the family lineage, inherited homes and land, cared for elderly parents and overseen funerals and ancestor worship rituals.