* Rumors have swirled since an operation in Cuba

* Venezuela government says rivals 'rubbing hands' in glee

* Opposition demands more details of his condition

CARACAS - Senior allies of Venezuela's socialist President Hugo Chavez have dismissed reports he is sicker than the government has admitted, telling his enemies to "stop dreaming" of his death.

The normally verbose leader has not been seen in public since a June 10 operation in Cuba to remove a pelvic swelling. His long absence has prompted widespread speculation he may be seriously ill, possibly being treated for prostate cancer.

Accusing opponents of cynically rejoicing at his health problems, government officials insist Chavez, 56, is fine and that he should be back for a regional summit planned for Venezuela's 200th anniversary of independence on July 5.

"President Chavez is recovering well from his surgery. His enemies should stop dreaming and his friends should stop worrying," Vice- Foreign Minister Temir Porras said on the social networking site Twitter.

"The only thing that has metastasized is the cancer of the Miami Herald and the rest of the right-wing press."

A report in the Nuevo Herald, the Miami Herald's Spanish-language sister paper, on Saturday cited unnamed U.S. intelligence officials as saying Chavez was in "critical condition" at a hospital in Havana.

A senior US official cast doubt on that report, telling Reuters that Washington was hearing lots of speculation about Chavez's health but had no firm intelligence.

"The fact is, we just don't know," the official said.

CANCER DENIAL

Fernando Soto Rojas, a Chavez ally who heads the National Assembly, said the president would be back before the summit scheduled for July 5-6 on Margarita island off Venezuela's Caribbean coast.

"Chavez is recuperating and we will have him here, thank God, on July 5," he told reporters on Sunday.

Asked if the president was being treated for cancer, Soto Rojas denied it and said: "I would be the first to tell the country" if that were the case.

The absence of Chavez, a former soldier who has nationalized much of the economy, has underlined his total dominance of Venezuelan politics, and the lack of any obvious successor after his 12 years in power.

Vice-President Elias Jaua said Chavez would return soon.

"The national and international right-wing are going crazy, rubbing their hands together ... even talking about the death of the president," he said in a speech, adding that Chavez's rivals were exposing themselves as anti-democratic fascists.

"They know they cannot win elections against our comandante," Jaua said.

Opposition politician Miguel Angel Rodriguez said the government was neglecting its constitutional obligations by not providing more detailed information on Chavez's condition.

"The uncertainty about the health of Hugo Chavez and the grave speculation about the true picture of what afflicts him reveals severe constitutional failures by the government in its duty to inform," Rodriguez said in a statement.

Chavez sent several Twitter messages on Friday from his @chavezcandanga account, which is followed by more than 1.6 million people, but said nothing about his health.

He continued tweeting on Saturday, expressing pride in a big new housing project and saying his daughter Rosines and grandchildren had flown to Cuba to visit him. "Ah, what happiness to receive this bath of love! God blesses me!" he wrote.