A human rights group Wednesday called for the release of hundreds of South Koreans jailed for dodging military service on conscientious grounds, seeing their imprisonment as a human rights violation. 

Compulsory military service has been a touchy subject in South Korea, where all able-bodied men must serve in the military for about two years and stay in the reserve forces for eight years.

The mandatory service was introduced after the 1950-53 Korean War ended in an armistice, not a peace treaty. South Korea remains technically at war with North Korea.

Criminalizing those who object to military duty, however, constitutes a violation of human rights, Amnesty International said in its latest report "Sentenced to Life," released at a press conference in Seoul.

South Korea currently imprisons more than 600 conscientious objectors, or more than the rest of the world put together, according to the report.

Most of them are Jehovah's Witnesses, a Christian group that opposes war, and in their early 20s.

Apart from South Korea, only four United Nations member states -- Eritrea, Singapore, Turkey and Turkmenistan -- are believed to have held conscientious objectors in prison as of 2013.

Song In-ho, 25, who declined to serve military duty because of his Christian beliefs, said he knew from an early age he would end up in jail.

"I was born a criminal. All my life I felt like I was imprisoned because I knew I would be sent to jail," Song, who now works for a cleaning company, was quoted as saying in the report.

"I was a future criminal."

Not only is rejecting military service shameful, it also spells the end of a prestigious career, Song said.

South Korea had at one point considered introducing alternative service for conscientious objectors as demanded by Amnesty International.

In 2007, the Ministry of National Defense made the pledge to do so in two years, but the plan fizzled after the Lee Myung-bak administration took power in 2008.

South Korea fears conscientious objection may jeopardize national security and undermine social cohesion.

A court ruling Tuesday challenged the view.

In the first ruling of its kind in eight years, the Gwangju District Court in South Jeolla Province acquitted three Jehovah's Witnesses of violating the Military Service Law.

"We need to harmonize the rights to conscience as stated in the constitution and the duty to serve in the military," Judge Choi Chang-seok said.

The Supreme Court is expected to throw out the acquittal, as it did in 2004 and 2007.

The Constitutional Court also ruled in 2004 and 2011 that punishing conscientious objectors is constitutional. (Yonhap)