28 November 2012 Last updated at 20:08 ET

Venezuela President Chavez arrives in Cuba for treatment

Hugo Chavez has travelled to Cuba many times since he was diagnosed with cancer in 2011

Venezuelan President Hugo Chavez has arrived in Cuba, where he had months of cancer therapy, for further medical treatment.

Mr Chavez, who was re-elected in October, is due to be sworn in for a third term in January.

In a letter to the National Assembly, Mr Chavez said he needed further therapy to recover from this year's "tough electoral campaign".

In May he declared himself free of cancer.

There is no indication in his letter that the cancer has returned.

But the opposition has called for transparency about his health and the nature of his treatment in Cuba.

"This secrecy always leaves doubts about how much truth there is in the government's statements," said opposition politician Ramon Guillermo Aveledo.

No photos or footage of the president's departure or arrival have been released.

Hugo Chavez's health

• 30 Jun 2011: Announces he underwent operation in Cuba to remove cancerous tumour
• Jul-Sep 2011: Has four rounds of chemotherapy
• Feb 2012: Flies to Cuba for surgery on "malignant" lesion in the pelvic region
• Apr-May 2012: Undergoes radiotherapy in Cuba
• 11 May 2012: Returns to Venezuela, hails treatment "success"

Mr Chavez, 58, was first diagnosed with an undisclosed cancer in June 2011.

He has since had repeated surgery in Cuba, but finished his treatment there earlier this year.

In his letter to the National Assembly on Tuesday, Mr Chavez said he was returning to Havana following medical advice.

"Six months after I had the last session of radiotherapy, I have been advised to begin a new special treatment, with several sessions of hyperbaric oxygen therapy and physiotherapy," says the letter.

The treatment is aimed at continuing to "consolidate recent health improvements," he added.

The left-wing president was first elected in 1998.

During the electoral campaign, he dismissed rumours that he had not been cured of his cancer, and vowed to serve out his six-year term.