As North Korea grappled with a massive famine in the 1990s, scientists were working at an elite institute to find ways to boost then leader Kim Jong Il's longevity — and his libido — a defector said Friday.

In the early 1990s scientists were sent to Denmark to find ways to improve the tenderness of North Korea's beef which Kim thought was too tough, said biologist Kim Hyeong Soo, who worked at the center for six years.

He told a human rights conference in London that some 130 scientists selected from the best universities worked at the center which was dedicated to promoting the health and longevity of North Korean founder Kim Il Sung and his son, Jong Il, who took over power in the secretive state in 1994 and who died in 2011.