MOSCOW, March 2 (RIA Novosti) - Venezuelan President Hugo Chavez is has been undergoing chemotherapy treatment and is continuing “his battle for life," the country’s vice president has said.

Vice President Nicolas Maduro’s comments, carried by the Associated Press, came late on Friday amid swirling rumors about the cancer-stricken Chavez, who has not been seen in public since heading to Cuba for treatment in mid-December.

Maduro was speaking after a Mass for Chavez in a chapel near the military hospital where authorities say the socialist leader has been since he returned to Caracas on February 18.

He quoted Chavez as saying he had decided to return to Venezuela to enter "a new phase" of "more intense and tough" treatments.

Opposition leader Henrique Capriles, defeated by Chavez in the country’s October presidential elections, had accused the government of lying about the socialist leader’s condition shortly before Maduro’s statement.

"We'll see how they explain to the country… all the lies they've been telling about the president's situation," Capriles said in a tweet.

But Maduro – Chavez's chosen successor – accused opponents of spreading false rumors about the president’s health to destabilize the country.

Chavez's son-in-law, Science Minister Jorge Arreaza, said on state television this week that the president continues "to fight hard and is in the military hospital, as peaceful as he could be, with his doctors, with his family."