Venezuela's president has been receiving chemotherapy since recovering from a severe respiratory infection in mid-January and "continues his battle for life", his vice president has said.
Nicolas Maduro said late on Friday Hugo Chavez, who is suffering from cancer, decided to return to Venezuela because he was entering "a new phase" of "more intense and tough" treatments.
Maduro suggested the chemotherapy was continuing in the government's first mention of it as among treatments that Chavez has received since his December 11 cancer surgery in Cuba.
The vice president made the disclosure after a Mass for Chavez in a new chapel outside the military hospital where authorities say the socialist leader has been since being flown back to Caracas on February 18.
The detailed rundown to date of Chavez's post-operative struggle came hours after an accusation by Henrique Capriles, leader of the opposition, that the government had repeatedly lied about Chavez's condition.
"We'll see how they explain to the country in the [coming] days all the lies they've been telling about the president's situation," Capriles, whom Chavez defeated in October 7 elections, said in a tweet.
Chavez has not been seen nor heard from since going to Cuba for his fourth cancer surgery, except for a set of "proof of life" photos released on February 15 while he was still in Havana.
The president revealed an unspecified cancer in the pelvic region in June 2011, and reported undergoing radiation treatment and chemotherapy after earlier operations.
The government has sent mixed signals on Chavez's condition, although Maduro has said several times that Chavez was battling for his life.
He repeated that on Friday, and also accused opponents of spreading rumours about Chavez's health to destabilise the nation.
When he went into the operating room in Havana on December 11, Maduro recalled, Chavez told his aides that there was a "possibility that he would not come out" alive, but he survived it.
At the end of the year, the 58-year-old leader's condition "worsened" due to a respiratory infection, and a tracheal tube was inserted later to assist his breathing.
But after a "general improvement" of his vital organs in January, Chavez and his doctors in Cuba decided to begin "complementary treatments, which is chemotherapy," the vice president said.