Caracas - Venezuelan President Hugo Chavez is suffering from a "new and severe" infection that has worsened his breathing as he undergoes intensive chemotherapy, the government said late on Monday.
The announcement came two weeks after Chavez, aged 58, checked into a Caracas military hospital following two months of treatment in Cuba, where he underwent his fourth round of cancer surgery since June 2011.
"Currently, he has a new, and severe infection," Information Minister Ernesto Villegas said in a statement read from the hospital, adding that there was a "worsening of respiratory function".
Villegas reiterated that Chavez was undergoing "intensive chemotherapy, as well as complementary treatments" and that his "condition continues to be very delicate".
"Comandante Chavez continues to cling to Christ and life, conscious of the difficulties that he is facing and strictly following the programme designed by the medical team," the minister said.
The government revealed for the first time on Friday that Chavez began receiving a tough new round of chemotherapy in Cuba after a respiratory infection had improved in January and decided to continue the treatment in Caracas.
The firebrand leader stealthily returned to the capital on 18 February, with a message on his Twitter account sent in the dead of night.
Chavez has not come out or spoken in public in almost three months, fuelling speculation about his health that has angered his government. Officials only released a set of photos showing him in his Havana hospital bed, smiling with two daughters on 15 February, three days before his homecoming.
The government has sent mixed messages about his condition, saying last week that he was still suffering from respiratory problems before declaring the next day that he had presided over a five-hour meeting with aides.
Then Vice President Nicolas Maduro, his chosen successor, disclosed the chemotherapy treatment late on Friday, before saying the next day that Chavez was still sending instructions about political and economic policies.
Maduro said Chavez was communicating by writing and other "creative" ways because a tracheal tube, which is assisting his breathing, was hindering his speech. He said the president was "in good spirits" while fighting for his life.
Hundreds of people joined an opposition-led march on Sunday demanding that the government reveal more details about the condition of the president of this South American nation which sits atop the world's largest proven oil reserves.
Rumours of death
The government has never disclosed the exact nature, location and severity of the cancer, only that it was in the pelvic region.
The opposition has accused the government of lying about the president's health, doubting that he could have held an hours long policy meeting.
Maduro and other senior officials lashed out at the opposition and rumours that the president may be dead, saying it was part of a campaign to destabilise the nation.
In power for 14 years, Chavez was re-elected to a six-year term in October but was unable to attend his 10 January inauguration.
Before he left for Cuba in December, he designated Maduro as his political heir and urged Venezuelans to vote for him if he is unable to resume his duties. The constitution says elections must be held within 30 days if the president becomes incapacitated.