Venezuela's government has published a decree signed by President Hugo Chavez, while his vice president said Wednesday that the ailing leader also sent a message of gratitude to the military for its loyalty.
Current Vice President Nicolas Maduro, who has been in charge of the country during Chavez's recovery, announced Jaua's appointment at a National Assembly session on Tuesday.
Chavez has not made any public comments since his operation last month, his fourth in 18 months. He has been fighting an unspecified type of pelvic cancer, and his silence has fed speculation about his medical condition.
Before the decree was published, the opposition had questioned the legality of the new foreign minister's appointment, citing a lack of publicly released documents with Chavez's signature.
The opposition has also been demanding more information about the president's condition.
"If the president of the republic can sign decrees, I call on him to appear, speak to Venezuela and talk about everything that's happening in that government," top opposition leader Henrique Capriles said Wednesday.
In a televised speech to soldiers, Maduro recalled meeting with Chavez in Havana earlier this week, saying the president was pleased with how his allies have been working together.
"We were with the commander in chief 48 hours ago, and yesterday we spoke with Minister Jorge Arreaza (Chavez's son-in-law), and he really feels great happiness to see, when we described how we've been interacting, the work we're doing constantly," Maduro said.
"He told us to transmit to the Bolivarian National Armed Force, from his heart, all his gratitude for so much loyalty from you all."
The government says Chavez is being treated for "respiratory deficiency," but it remains unclear how much longer he could remain in hospital in Cuba.
Addressing the troops, Defense Minister Diego Molero said the military will be watching for any "disturbance" of public order.
The opposition has called for a protest in Caracas on Jan. 23 to denounce what it called an unconstitutional postponement of Chavez's inauguration. The government says it is also organizing demonstrations on that date, the anniversary of the fall of the country's last dictatorship in 1958.