Venezuelan President Hugo Chavez is undergoing a new round of "hard and complex" treatment after cancer surgery in Cuba, Vice President Nicolas Maduro said Wednesday.

"You all know that we had a very difficult time during the post-surgery period in last December and January," Maduro told national television. "Today, the commander (Chavez) has begun the complementary treatment, which is very hard and complex."

Chavez, 58, has been battling with cancer since first being diagnosed in June 2011, and underwent a fourth round of surgery on Dec. 11.

His prolonged absence from the public has fueled rumors about his state of health, including allegations from opponents that he was on life support.