Hugo Chavez, the Venezuelan president, has delegated some powers to his vice-president and the finance minister, a day after announcing he will return to Cuba to begin a new phase of cancer treatment.

Chavez has resisted calls from the opposition to temporarily handover the presidency to Elias Jaua, the vice-president, but gave him and Jorge Giordani, the finance minister, powers that include budgetary matters.

The president, who had a large tumour removed last month in Cuba, said on Friday he was going back to Havana to begin what "we've called the second phase." It will include chemotherapy.

He announced his plans on Friday after meeting Ollanta Humala, the Peruvian president-elect.

Chavez said he will send a letter to the president of Venezuela's national assembly to secure authorisation for his trip out of the country, as required by the constitution.

The move comes in the wake of speculation that Chavez will travel to Brazil for treatment at the Sirio-Libanes hospital, considered one of the best in Latin America and renowned for its cancer centre.

Earlier this month, the Venezuelan leader admitted in a television address that he had a tumour but had undergone a successful operation in Cuba to extract the cancerous cells.

This was his first televised speech to the nation, weeks after he was hospitalised in Havana, sparking widespread speculation about his health.

"They confirmed the existence of a tumourous abscess, with the presence of cancerous cells, which required another operation to extract the tumour completely," he had said.

Barely two days after the speech from Cuba, Chavez arrived at Maiquetia airport outside Caracas, the capital, as the country was preparing to celebrate the 200th anniversary of its independence from Spain.

Addressing his supporters from the balcony of his presidential palace, Chavez vowed to win the battle to regain his health.

He thanked Fidel Castro, the iconic Cuban leader, saying that the veteran leader has been practically his "medical chief" while recovering in Cuba. He said he will "win this battle for life."

Chavez's announcement that he had cancer shocked the country of 29 million people and upended the OPEC nation's politics, which he has dominated for 12 years.

It raised questions about whether Chavez will be able to run for re-election next year.

Last month, Venezuela's government postponed a regional summit, citing Chavez's health.

Ever since the 56-year-old leader was rushed into emergency surgery on June 10, news about his health has been a matter of great speculation, and even his close aides have little clue about the seriousness of his disease.

He has not said what type of cancer he has or for how long he will be out of the country.