Chavez, who led a failed putsch himself before winning the presidency at the ballot box and then survived a brief coup once in power, denounced what his opponent says is a plan to organise street protests if Chavez wins by fraud.
"They are already calling for violence, already calling for a coup d'etat," Chavez said at a news conference with foreign reporters.
"We are going to prepare a plan of counterattack," he added. "... (If) they go onto the streets and block roads and throw stuff and set things on fire, we would be obliged to impose order," he added.
Opposition candidate Manuel Rosales, who trails far behind Chavez in opinion polls, has said if Chavez tries to steal the election, his supporters would hold peaceful marches demanding a fair count.
But Chavez, who frequently makes wild accusations without providing evidence such as the United States wanting to assassinate him, said the opposition had a three-day plan to instigate a coup.
On December 3, the day of the vote, the opposition, which has complained of fraud in previous votes, will claim the election was stolen, the former army colonel said. The next day, they will bring people onto the streets and the day after, they want to call out the armed forces, he added.
Rosales, the governor of an oil-producing state, has requested a meeting with senior military officers.
But Chavez has said the armed forces have to support his self-styled revolution and publicly accused one officer of holding a suspicious meeting with his opponent's camp.
The president has tried to paint his challenger as anti-democratic and his campaign ads show images of Rosales shaking hands with the man chosen to head the government when Chavez was ousted by a coup for two days in 2002.
The anti-American president says Rosales is backed by the United States, which was the only member of the Organisation of American States that did not immediately condemn the coup.
Rosales echoes US charges that Chavez, the top ally of Cuban President Fidel Castro, is anti-democratic and exerting increasing control over Venezuelan institutions.

POST-ELECTION FEARS
Chavez's coup accusations could stoke fears in a polarised country, where many Venezuelans typically stockpile food and emergency items such as torches in case of any breakdown in order after elections.
Independent polls show Chavez coasting to victory because of the majority poor's support for his free spending of oil revenue on health and education programs.
Still, some opposition-linked polls have raised optimism among Rosales' supporters that he can win because he has united the opposition with a campaign focused on the incumbent's weaknesses on unemployment and crime.
Chavez said the surveys, including from US pollsters, were slanted to create a false impression of a tight race and prepare the groundwork for voting-day fraud claims.
In 2004, opposition-linked polls showed Chavez losing a recall referendum and the opposition then said he won through fraud, even though international observers declared his big victory was fair.
Last year, only days before a legislative election, the opposition withdrew, claiming the results would be fraudulent.
As it did with that vote, the government has denied US media reports that the makers of the electronic voting machines used in Venezuelan elections are linked to Chavez's camp.
"If we beat them again, I call on them to show -- for the first time in years -- they are men of honour and recognise reality," Chavez said.

Copyright Reuters, 2006