Chavez flies back to Cuba to undergo chemotherapy after tumour removed

Chavez has kept a lid on information about his health problems over the past month but has made headlines with unexpected announcements and appearances, including a recent dawn telephone interview broadcast on state television.

The announcement that he would travel to Cuba for treatment came after he met with Peruvian president-elect Ollanta Humala.

Chavez spent much of June in the Cuban capital, Havana, undergoing surgery to remove an abscess and a tumour in his pelvic region before making a surprise return home on 4 July. Speaking on the steps of the presidential palace, Chavez said: "This second phase will begin in the next days with the application of chemotherapy, scientifically planned, in detail.

"I am sure, I repeat, that the second stage will contribute to following the path to the recuperation of my health."

It is not clear how long he plans to remain in Cuba, a close political ally now under the leadership of Raul Castro.

Venezuela's opposition leader Alfonso Marquina said vice president Elias Jaua should temporarily assume Chavez's duties.

Chavez's cancer diagnosis has thrown uncertainty into Venezuela's political landscape. The 56-year-old, who has held dominant power during more than 12 years in office, has said he is confident he will rebound but has also admitted he faces a long road to recovery.

Chavez had surgery in Cuba on 20 June to remove a tumour. He has said the baseball-sized growth was removed but has given no further details. It has been suggested he is suffering from cancer of the colon. He received a hero's welcome from supporters upon his return and has since kept up near daily public appearances. He has rallied crowds from the presidential palace and in a downtown plaza, presided at cabinet meetings, addressed troops and generally sought to reassure Venezuelans that he is firmly in control in spite of his illness.

Yet he has also reminded his audiences of the challenges he faces, frequently saying he is fighting for his life and is under doctors' orders not to overexert himself. He acknowledged last Wednesday for the first time that he expected to undergo chemotherapy or radiation treatment, which he said would "armour the body against new malignant cells."

During the past two weeks he has also appeared on television, leading cabinet meetings and attending Mass.

Chavez, who is up for re-election next year, has sought to project confidence while often telling supporters: "We will live!"