Venezuelan President Hugo Chavez has said he is travelling back to Cuba for another round of cancer treatment.

"I leave this afternoon for Havana... to continue with my radiation treatment," Chavez said in a televised speech on Saturday before leaving the Miraflores Palace.

"There are five sessions of radiotherapy ... for five consecutive days, then two days of rest ... With this I have faith that [the cancer] inside my body will not return."

The 57-year-old leftist president, in office since 1999, has vowed to overcome cancer to win another six-year term in elections on October 7.

Chavez completed the first round in Havana, where he had surgery last month to remove a malignant tumor in the same area where another tumor was excised in June 2011.

Officials in Caracas have never specified the type of cancer the president has, but insist it has not spread to other organs.

His prior stay in Havana lasted exactly five days, allowing him to head off criticism that he had left Venezuela without permission from the National Assembly, which must authorise a president's absence if it exceeds that length of time.

The cancer comes at an awkward time for Chavez, who is in the thick of what is expected to be a tough re-election campaign. He has ruled out the possibility of a replacement candidate.

Chavez faces a stiff challenge from 39-year-old state governor Henrique Capriles, who was chosen to represent a unified opposition in primaries earlier this year.

Source: Agencies