South Korea's top conglomerate Samsung Group said Wednesday its head Lee Kun-hee, recuperating from a heart attack last May, is still undergoing rehabilitation without any marked change in health condition.

"The chairman's health has not seen any significant changes in the new year, and there is nothing to explain," said Lee Jun, the top communications official of Samsung Group.

Lee was rushed to a hospital near his home in Seoul on May 10 after experiencing difficulty breathing and was later confirmed to have suffered a heart attack.

The group was expected to skip the celebration of the tycoon's 73rd birthday on Friday, an annual event held in lavish style with senior executives invited to an expensive dinner and performance.

Lee's only son, Jay-yong, has since stepped in, meeting with corporate counterparts and attending meetings.

The latest update on Lee's health was in last November, when Samsung said he was awake 15-19 hours a day and exercising on a wheelchair. (Yonhap)