Venezuelan President Hugo Chavez, who is recovering from cancer surgery in Cuba, will not attend his inauguration ceremony on Thursday, Vice-President Nicolas Maduro announced Tuesday, DPA reported.
"The president has asked us to inform that in agreement with the recommendations of the medical team watching over the recovery of his health, the process of post-surgery recovery must extend beyond January 10," Maduro said in a communique to parliament.
Chavez will take his oath later on before the Supreme Court, said Maduro, whom Chavez has appointed his successor.
His letter was read out by parliament president Diosdado Cabello, while pro-Chavez legislators cheered and the opposition booed.
The opposition has criticized the government over plans to delay the inauguration and charged that it would violate the constitution.
Chavez was due to be sworn in for a fourth term on Thursday, after winning the elections in October.
However, the 58-year-old left-wing nationalist leader is being treated for cancer in Cuba. Last week he suffered respiratory failure. He has not been seen in public since mid-December.
The opposition alliance, the Democratic Unity Roundtable (MUD), sent a letter to Jose Miguel Insulza, secretary-general of the Organization of American States, saying that delaying the inauguration would violate the constitution.
The constitution excludes a power vacuum and says that in a situation such as the one now facing Venezuela, Cabello should temporarily take power, MUD leader Ramon Guillermo Aveledo said in the letter.
Henrique Capriles Radonski, the main opposition candidate in the October elections, called on the Supreme Court to take a stance.
The opposition has earlier called for new elections to be held.
Prosecutors meanwhile announced that they were investigating possible incitement to terrorism through social networking sites such as Twitter in spreading rumours about Chavez' health.
Police searched the home of Federico Medina Ravell, the public prosecutor's office said. Medina Ravell is cousin of journalist Alberto Federico Ravell, who has earlier been accused of trying to "destabilize" the Venezuelan government.
US State Department spokesman Victoria Nuland said Chavez' inauguration was an issue for Venezuelans to decide, and that they "need to do it in a manner that includes all the voices in the discussion."
Marco Aurelio Garcia, an international affairs advisor to Brazilian President Dilma Rousseff, told the daily Folha de Sao Paulo that Brazil agreed with postponing the ceremony.
Cabello earlier said that several leaders were expected to arrive in Caracas by Thursday to "visit us and show their solidarity to commander Chavez."
Uruguayan President Jose Mujica, Bolivian President Evo Morales and Ecuadorian Foreign Minister Ricardo Patino were among those expected in the Venezuelan capital.
Argentine President Cristina Fernandez is to make a private visit to Havana to see Chavez on Friday, sources from her office said.
Venezuelan Information Minister Ernesto Villegas said Chavez was in a stable condition.