* If Chavez steps down, Maduro likely to face Capriles
* President hasn't been seen or heard from in eight weeks
Venezuelan Vice President Nicolas Maduro accused opposition leader Henrique Capriles on Saturday of "conspiring" against the OPEC nation during meetings in neighboring Colombia, stepping up his attacks on his most likely potential election rival.
The government is upbeat about President Hugo Chavez's recovery from cancer surgery in Cuba. But the socialist maverick has not been seen in public or heard from in eight weeks, calling into question the future of his self-styled revolution.
Any new vote in South America's top oil exporter would probably pit Maduro, Chavez's heir apparent, against Capriles, the 40-year-old governor of Miranda state, who lost to Chavez in last October's presidential election.
Maduro has been sharpening his rhetoric against the opposition leader, and the former bus driver said on Saturday he was being kept informed about a series of meetings Capriles was holding during a trip to Colombia that began on Friday.
"The information reaching us is not good," Maduro said, wearing a hard hat during a televised visit to a tractor factory in Portuguesa state, in the west of the country.
"We know who he met with, and where, conspiring against the country and against peace ... in a few hours we are going to say what that loser was doing against the fatherland in Colombia."
Earlier this week, the vice president said "honest, patriotic" lawmakers from the ruling party would present proof next Tuesday of "immense corruption" involving a senior figure in Primero Justicia, the party Capriles helped found in 2000.
There was no immediate response from opposition officials.
Opposition leaders, who accuse the government of secrecy over Chavez's condition, say Maduro is in campaign mode and merely seeking to imitate his boss' vitriolic attacks on them.
The government, which says it has never been more transparent about the 58-year-old leader's health, says Chavez has completed a complex post-operative period following the Dec. 11 surgery, and has started a "new phase" of his recuperation.
Maduro said Chavez was recovering gradually and held talks in Havana on Friday with Diosdado Cabello, the head of the National Assembly, and Defense Minister Diego Molero.
The president has never said exactly what type of cancer he is suffering, only that it was diagnosed in his pelvis in mid-2011. He has since undergone four operations in Cuba, and weeks of chemotherapy and radiation treatment.
While his fragile health could spell an end to Chavez's 14 years in power, the pressures of the situation have exposed old strains between moderates and more hard-line members of the opposition's five-year-old Democratic Unity coalition.
It is made up of some 30 ideologically diverse political groups that chose Capriles as a unity candidate to run against Chavez in last year's election.
Despite their differences, they are likely to pick Capriles again to face Maduro, should Chavez step down or die and a new vote was held within 30 days, as laid out in the constitution.
After chatting with workers and inspecting farm machinery in Portuguesa, the vice president slammed Capriles and two other top opposition figures: the coalition's policy architect, Ramon Guillermo Aveledo, and Caracas Mayor Antonio Ledezma
"They're a trio of wrecks with a history of defeat and treason," Maduro said. "They must know that if our people see the proof that has been prepared of their plot ... it is just going to radicalize us even more."
During Capriles' absence in Colombia on Friday, the government launched a high-profile anti-crime operation involving more than 2,000 officers in his state, Miranda, which includes crime-ridden parts of the capital, Caracas.
The interior and justice minister, Nestor Reverol, used the event to criticize the opposition governor for his trip outside the country.
"Instead of being in Colombia, meeting the paramilitaries, you should be here supervising the deployment and ensuring people's safety," Reverol said on state TV, flanked by commanders of the security forces on a podium alongside National Guard troops lined up on motorcycles.