Venezuelan President Hugo Chávez will not attend a regional trade summit in Brazil, sources said.

Before he went to Cuba last week for more cancer-related treatment, Chávez had spoken enthusiastically about attending the Mercosur bloc's meeting in Brasilia to celebrate Venezuela's entry.

He has not been seen in public since Nov. 15.

"Chávez is not coming. They've even canceled the hotel reservation," a Brazilian foreign ministry source said. Another Brazilian official said Chavez's logistics and security advance staff were leaving Brasilia.

In Caracas, a source at the Miraflores presidential palace also said the 58-year-old Cáavez was not going to travel.

The recently re-elected president went to Cuba nine days ago for "hyperbaric oxygenation" treatment - normally used to treat bone decay caused by radiation therapy.

Chávez has had three cancer surgeries in Cuba since mid-2011. So even though officials were portraying the latest treatment as normal follow-up after radiation, rumors are rampant that it could be more serious.

Officials have given no detailed information on Chávez's condition.

Later on Thursday, Venezuela's information minister tweeted links to two statements by the president, one extolling a group of colorful Venezuelan cultural dancers, Los Danzantes de Corpus Christi, and another expressing his regret at the death of Brazilian architect Oscar Niemeyer on Wednesday.

Neither statement mentioned Chávez's health, his treatment in Cuba, nor his absence from the meeting in Brasilia.

His presence in Cuba, where Chávez has spent more than three months in total since his first 2011 diagnosis of cancer in the pelvic region, has overshadowed Dec. 16 regional elections.

Without him on the campaign trail or television, the race for 23 governorships has been a low-key one, failing to light up the public like October's presidential election did with a record voter turnout of more than 80 percent.

Although Chávez continues to sign official papers and make appointments from Cuba, his absence may delay decisions on some major issues like a possible devaluation of the bolivar currency or an amnesty for jailed opponents.

Various ministers have been visiting him in Havana this week, according to Venezuelan officials.

Chávez allies have lambasted media and others for behaving like "vampires" with speculation about his condition. One pro-opposition journalist said he was using a wheelchair.