Chavez appears on TV and says he underwent surgery for cancer

The announcement from Cuba confirmed rumours swirling for nearly three weeks but still stunned Venezuelans ahead of what was already looking like a tight race for a presidential election next year.

Speaking from Havana where he underwent surgery on June 10, a pale and emotional Chavez gave no indication when he would return to Venezuela. Nor did he name a temporary substitute to lead the polarized nation of 29 million people.

"They confirmed the existence of a tumorous abscess, with the presence of cancerous cells, which needed another operation to extract the tumour completely," he said in his first address to the nation since his surgery.

Chavez, 56, said he was receiving "complementary treatments to combat different types of cells that were found" -- possibly implying chemotherapy.

"I deeply appreciate the demonstrations of solidarity by Venezuelans and other brotherly people," he added, standing at a lectern by a Venezuelan flag and a painting of his inspiration, South American independence hero Simon Bolivar.

Analysts say a prolonged absence could trigger infighting among his allies -- none of whom possess Chavez's charisma or national appeal -- and possibly prompt calls for an early election by opposition parties gearing up for a 2012 poll.

"It is impossible to deduce if he will or will not be in a physical state and the right mood to go into the 2012 campaign," said local analyst Luis-Vicente Leon said.

During his 12-year rule, Chavez alienated many for nationalizing large swathes of the economy and showing an authoritarian streak both in his stranglehold on government and his tough treatment of political opponents.