President Hugo Chavez of Venezuela suffered bleeding during surgery for cancer in Cuba on Tuesday, but is said to be recovering well.
Communications Minister Ernesto Villegas said the president will require "proper time" to recover because of the complexity of the surgery and its complications.
This is the fourth operation for Mr Chavez since last year. The cancer was first detected during initial surgery for a pelvic abscess in June 2011.
In a statement, Mr Villegas called on Venezuelans to continue praying for Mr Chavez, 58, who "suffered bleeding that required the use of corrective measures", he said.
Vice-President Nicolas Maduro says the condition of Mr Chavez has improved "from stable to favourable".
On Wednesday, Mr Maduro said the president's latest surgery had been "complex, difficult, delicate" and he faced a "complex" recovery.
The president, who was re-elected to a fourth term in October, is due to take office on 10 January for a six-year term.
The Venezuelan constitution states that, should the president leave office in the first four years of his term, an election must be held within 30 days.
Mr Maduro, a former bus driver, is one of the president's closest advisers.
The Venezuelan government has been giving daily updates on the president's health, unlike during his previous visits to Cuba.
The BBC corrspondent says it may be preparing the Venezuelan people for the possibility of Mr Chavez's "socialist revolution" having to go on without him.