Venezuelan President Hugo Chavez has revealed he has had surgery to remove a cancerous tumour, in his first speech since flying to Cuba for treatment.
Speculation about his health had been rife since he left Venezuela three weeks ago for what officials said was an operation on a pelvic abscess.
Mr Chavez said he was determined to overcome his health battle and was now on the road to "full recovery".
His absence forced Venezuela to put off a regional meeting on Wednesday.
Looking much thinner than when he last addressed the nation, Mr Chavez confirmed what many had suspected - his health problems were more serious than first thought, says the BBC's Sarah Grainger in Caracas.
Standing behind a podium, the president said he had made the "fundamental error" of failing to look after himself.
Former Cuban President Fidel Castro had first told him he had looked unwell while he was on a state visit to Havana, he added.
Mr Chavez said he underwent a first operation on a pelvic abscess on 10 June, just as officials had informed the Venezuelan public.
But during his recuperation, tests had "confirmed the existence of a tumour with cancerous cells", forcing him to undergo another operation. The extraction of the tumour had been "completely successful", he said.
He added that his condition had been "evolving satisfactorily" while he received a "complementary treatment to combat the different types of cells found, and thereby continue on the path to my full recovery".
"I deeply appreciate the demonstrations of solidarity by Venezuelans and other brotherly people," he said.
Mr Chavez called it a "new battle that life has placed before us", and ended the speech with the revolutionary slogan often used by Mr Castro: "Forever onward toward victory! We will be victorious! Until my return!"
The address was aired by the pan-American channel Telesur late on Thursday. It is unclear when it was recorded. Screen captions indicated that he was speaking from Cuba.
Afterwards, Venezuela's vice-president said the government was united and that Mr Chavez's reforms would be "deepened" despite his ill-health.
"This is not the time to go backward, it's time to advance," Elias Jaua said.
Mr Chavez did not say how much longer he expected to remain in Cuba recovering, but our correspondent says everyone hopes he will be back in Venezuela on Tuesday, when it celebrates 200 years of independence.