CARACAS, Venezuela  President Hugo Chávez has used his decree powers to carry out a major overhaul of this country’s intelligence agencies, provoking a fierce backlash here from human rights groups and legal scholars who say the measures will force citizens to inform on one another to avoid prison terms.

Under the new intelligence law, which took effect last week, Venezuela’s two main intelligence services, the DISIP secret police and the DIM military intelligence agency, will be replaced with new agencies, the General Intelligence Office and General Counterintelligence Office, under the control of Mr. Chávez.

The new law requires people in the country to comply with requests to assist the agencies, secret police or community activist groups loyal to Mr. Chávez. Refusal can result in prison terms of two to four years for most people and four to six years for government employees.

“We are before a set of measures that are a threat to all of us,” said Blanca Rosa Mármol de León, a justice on Venezuela’s top court, in a rare public judicial dissent. “I have an obligation to say this, as a citizen and a judge. This is a step toward the creation of a society of informers.”