Venezuela's vice-president, Nicolas Maduro, says the government of President Hugo Chavez is expelling two U.S. Embassy officials for meeting with military officers and planning to destabilize the country.
Maduro identified one American as the Air Force attache and said he had been spying on the military. He said the official has 24 hours to leave the country.
U.S. Embassy spokesman Greg Adams identified that attache as David Delmonaco.
Maduro spoke hours after the government said Chavez was in "very delicate" health after undergoing cancer surgery in December.
Maduro accused Venezuela's "historic enemies" of being behind Chavez's the cancer. Maduro said a scientific commission would be formed and that it would reveal that "Chavez was attacked with this disease... The historic enemies of this nation looked for how to harm the health of our commander."
Starting Monday, political and military leaders gathered at the presidential palace and supporters wept after the government said Chavez suffered a serious setback in his battle against cancer.
Some loyal "Chavistas" took to the streets in downtown Caracas, blowing whistles and horns, as rumors swirled that the socialist leader's 14-year rule of the OPEC nation could be nearing an end.
The government said late on Monday that his breathing problems had worsened and he was suffering a severe new respiratory infection.
The 58-year-old president has not been seen in public nor heard from since undergoing surgery in Cuba on Dec. 11, his fourth operation since the disease was detected in his pelvic area in mid-2011.
"God's will be done," said Maria Fernandez, 33, who works as a volunteer at a Socialist Party office that occupies Chavez's boyhood home in the village of Sabaneta. "We are just praying for him, as we have always done."
Several dozen people gathered from early morning at the Catholic chapel in the military hospital where Chavez has spent the last two weeks since returning from Cuba. Some prayed aloud, while others wept quietly.
The government has repeatedly said Chavez is fighting for his life. Though vague about medical details, officials have said he is breathing through a tracheal tube, unable to speak, and undergoing a new round of chemotherapy.
The government is furious at speculation, particularly among pro-opposition media, that Chavez may already be dead. Opposition leader Henrique Capriles has repeatedly accused Maduro and others of lying about Chavez's condition.
"They never change, that hatred they have shown Chavez all these years. It annoys them that Chavez does not give up, nor the people," Information Minister Ernesto Villegas said.
Chavez is adored by many poor Venezuelans for his humble roots, earthy rhetoric and oil-financed welfare policies. But opponents view Chavez as a dictatorial leader who has ruined the economy.
Chavez suffered multiple complications after the Dec. 11 surgery, including unexpected bleeding and an earlier severe respiratory infection that officials said had been controlled.
In the communique on Monday night, Villegas said his respiration had worsened and it was related to a depressed immune system. "There is now a new, severe infection," he added.
"The commander-president remains clinging to Christ and to life, conscious of the difficulties he is facing, and complying strictly with the program designed by his medical team."
Chavez has undergone several grueling rounds of chemotherapy and radiation treatment, which at times left him bald and bloated. He twice wrongly declared himself cured.
Some medical experts said they doubted Chavez was strong enough to sustain more chemotherapy at the moment.
The only sight the public has had of the former soldier since his latest operation were four photos published by the government while he was still in Havana that show him lying in a hospital bed.
Dozens of student demonstrators have been holding protests around Venezuela, including chaining themselves, to demand proof Chavez is alive and more detailed medical information.
"The lack of precise information worries Venezuelans and contributes to the rumors," said Ramon Guillermo Aveledo, executive-secretary of the opposition Democratic Unity coalition. He also lambasted the government's aggressive line toward opposition politicians in recent days.
Maduro and other senior officials have been haranguing the opposition daily as "fascists" and "conspirators" exulting in Chavez's suffering and plotting to destabilize Venezuela.
Should the Venezuelan leader step down or die, an election would be held within 30 days and would probably pit Maduro against Capriles. Polls show Maduro is the favorite, helped by Chavez's personal endorsement as his successor.
The stakes are high, too, for other left-leaning nations around Latin America and the Caribbean. Chavez's oil-financed largess has boosted economies of allies from Cuba and Nicaragua, to Bolivia and Ecuador.