CARACAS (Reuters) - President Hugo Chavez's breathing problems have worsened and he is suffering from a new, severe respiratory infection after undergoing cancer surgery in Cuba, Venezuela's government said in a somber update on Monday.

Reading the latest official assessment of Chavez's health, Information Minister Ernesto Villegas said the 58-year-old socialist leader's condition was very delicate.

"Today there is a worsening of his respiratory function. Related to his depressed immune system, there is now a new, severe infection," Villegas said.

"The president has been receiving high-impact chemotherapy, along with other complementary treatments ... his general condition continues to be very delicate."

Chavez made a surprise pre-dawn return to Venezuela from Cuba two weeks ago. The government said he is in a tightly guarded suite at a Caracas military hospital.

He has not been seen in public nor heard from since his December 11 operation in Havana, his fourth cancer surgery since the disease was detected in his pelvic region in mid-2011.

(Reporting by Daniel Wallis; Editing by Eric Walsh and Christopher Wilson)