The National Intelligence Service says North Korean leader Kim Jong-il is recovering after surgery on his circulatory system.

NIS director Kim Sung-ho told the National Assembly Intelligence Committee Wednesday that the North Korean leader had the surgery in mid-August and is now recuperating.

The director said the North Korean leader has not been seen in public since August 14 and received the surgery after he went out of public view.

Lawmakers who attended the parliamentary session quoted the intelligence chief as saying that the circulatory problem the North Korean leader suffered was a stroke.

It is said that Kim's condition has improved much and that he is able to govern his country.

The NIS director also said he reported the North Korean leader's sickness to President Lee Myung-bak immediately after he got the information on August 14. He said his agency is trying to investigate the North Korean situation further.

The 66-year-old reclusive North Korean leader is said to have diabetes and heart problems.