South Korean officials are keeping a close eye on Kim Ok amid some intelligence reports that she is not only nursing the ailing leader but also is signing official documents on his behalf.

Experts believe the communist leader is retaining a firm grip on power, running the nation from his bed with the help of military and communist party chiefs in line with the nation’s “songun,” or military first, policy. But they are not discounting the role of the woman who is seen by some as the de facto first lady.

“She is the closest person personally to Kim Jong Il,” said Marcus Noland, a North Korea expert at the Peterson Institute for International Economics in Washington. “In some ways, she’s the one guarding the bedroom or hospital door. She would be in a position to convey his preferences.”

Kim, 66, reportedly suffered a stroke last month and is recuperating following emergency brain surgery — though North Korean officials deny the communist leader, who was last seen in public more than a month ago, is ill.

Kim Jong Il was groomed for 20 years to take over as leader, assuming the mantle after his father’s death in 1994 in the communist world’s first hereditary transfer of power.

He has three sons — Jong Nam, Jong Chul and Jong Un — but does not appear to have anointed any of them as his heir-apparent. And Kim Ok may be poised to fill any void.

Experts speculate the North Korean leader’s dependence on her during his illness may further bolster her political clout. “If Kim Jong Il can’t communicate with others, her role will be larger,” said Kang Jung-mo, a North Korea expert at Kyung Hee University.

Little is known about her. Kim Jong Il is believed to have had three wives before taking Kim Ok as his consort several years ago. She reportedly accompanied the leader on his secret visit to China in 2006. She is said to be a pianist in her 40s who has served as the leader’s secretary since the 1980s.

Furthering the intrigue, Kim’s late wife, Ko Yong Hi, mother of his two younger sons, hand-picked Kim Ok to replace her when she was dying of cancer, according to South Korea’s JoongAng Ilbo newspaper.