SEOUL (AFP) - A once-hugely popular Korean-American singer, who was vilified for giving up his South Korean citizenship to avoid military service, lost his legal bid Friday (Sept 30) to be allowed back in the country.

Just as he was about to be called up in 2002, pop singer Steve Yoo, better known in South Korea as Yoo Seung Joon, gave up his Korean nationality and became a naturalised US citizen.

The South Korean government considered it an act of desertion and he was deported and banned from returning for life.

In an effort to overturn the ban, Yoo had filed a lawsuit with the Seoul Administrative Court, challenging the decision of a South Korean consulate in the United States to deny him a visa.

But the court ruled against him on Friday.

"If Yoo returns to South Korea and resumes activities, it will demoralise soldiers who are devoting themselves to serving the country, while provoking teenagers to evade the conscription," the Yonhap news agency quoted the ruling as saying.

More than 60 years after the end of the Korean War, every South Korean man between the age of 18 and 35 is required to perform two years of military service.

The main rationale is the continued threat from nuclear-armed North Korea, given that the 1950-53 Korean conflict ended with a ceasefire rather than a peace treaty, leaving the two Koreas technically at war.

For many, the two-year duty is an unwanted and deeply resented intrusion that interferes with studies or nascent careers and serves no discernible purpose, especially in a rapidly-ageing society where the size of the workforce is dwindling.

Hundreds try and avoid the draft every year, using tactics that range from extended overseas study, to starving themselves so that they fail the medical.

Other examples include the members of a break-dancing troupe arrested for pretending to have mental disorders, and a student who intentionally dislocated his shoulder and underwent surgery so as to fail the medical exam.

Some years ago, there was a mini-fad for large tattoos, which carry an organised-crime association in South Korea and can result in people being declared unsuitable for military service.

The loophole was effectively closed by a series of arrests of young men opting for last-minute all-body tattoos, who were then charged with "wilfully tampering" with their bodies to avoid service and jailed.

Top celebrities can face a powerful public backlash if they are seen to be flouting military service regulations in any way.

Pop icon Rain was pilloried after it emerged that he had been allowed to slip out of barracks on several occasions to meet an actress he was dating.

And "Gangnam Style" star Psy was forced to serve twice after he was found to have been furthering his showbiz interests during his first stint.