Venezuela's President Hugo Chavez has not revealed what kind of cancer he has. (Jorge Silva/Reuters)

Venezuelan President Hugo Chavez bid an emotional farewell laced with references to Jesus Christ and independence hero Simon Bolivar as he departed Venezuela on Friday for Cuba for urgent surgery to remove a tumour he says is probably malignant.

Last October, he declared himself cancer-free after surgery and chemotherapy in Cuba.

On Friday, clasping the hand of his youngest daughter, Chavez addressed allies of his socialist political movement and troops standing at attention at the Miraflores presidential palace.

"I say this from my gut: With cancer or without cancer ... come rain, thunder or lightning ... nobody can avoid a great patriotic victory Oct. 7," the president said, referring to the date of Venezuela's presidential election.

"Long live Chavez!" he cried.

The socialist president, who is seeking a fourth term, referenced Bolivar and Christ's burdens to describe his battle with cancer.

"Our [founding] father Simon Bolivar once said, 'I am a man of troubles.' I say as a son of Bolivar, I too am a man of troubles. We are a people of troubles," Chavez said.

Chavez's black SUV left the palace and rolled slowly through the capital, with red-shirted bodyguards clinging to the running boards, sticking out of the sunroof, the firebrand president waved to onlookers lining the avenues and people flying Venezuelan flags from rooftops.

A motorcade of white vans and police vehicles with flashing lights followed Chavez to the airport, where he shook hands with officials and spoke briefly before taking off for Cuba in the presidential plane.

Chavez, 57, is turning to the same Cuban doctors who extracted a baseball-size cancerous tumour from his pelvic region last summer. This time, the growth is smaller, two centimetres in diameter

Cuba and Venezuela are staunch allies, and Chavez enjoys a warm relationship with former leader Fidel Castro and his brother, President Raul Castro.

The Venezuelan president has not disclosed the precise location of either tumour, nor said what kind of cancer he had, but described next week's surgery as urgent.

Latin America's top cancer doctor, Paulo Hoff, who heads the cancer centre at Sao Paulo's Sirio-Libanes hospital, considered the region's best, would not talk specifically about Chavez's case. But he did say that a cancerous tumour in the pelvic region would be mainly limited to four types: prostate, rectal, bladder and sarcoma, the latter being a rare and deadly form of tumour.

Chavez allies have accused their political foes of hoping the president will die, opening a door for the opposition to win the Oct. 7 presidential vote.

Rival candidate Henrique Capriles has rejected such allegations and said he wishes for a Chavez recovery so Capriles can triumph "fair and square."

As Chavez's motorcade travelled through the streets, hundreds of supporters covered his SUV with flowers and even a portrait of Jesus that read: "I will heal you. Forward, commander!"

Chavez plans to continue governing from Cuba instead of delegating authority temporarily to Vice-President Elias Jaua. He has not said when he might return to Venezuela.