Police used tear gas, plastic bullets and water cannons to scatter hundreds of students protesting against the government Thursday, while President Hugo Chavez's supporters celebrated the 18th anniversary of his failed coup as an army officer.

Caracas Police Chief Carlos Meza said authorities broke up the protest because university students had not been granted permission to march. He said the denial was aimed at preventing clashes with thousands of "Chavistas" marching across the capital to mark the botched 1992 military rebellion that Chavez led as a lieutenant colonel.

"They don't have permission to march," Meza said.

Student leaders countered that they have the right to stage peaceful protests, and they said authorities loyal to Chavez frequently deny them permission to demonstrate. Before the protest was dispersed, students chanted: "We're students, not coup plotters!"

"This is one more demonstration of the government's abuse of power," student leader Roderick Navarro said.

Students started leading protests last week after the government pressured cable and satellite TV providers to drop an opposition channel. Students have organized demonstrations in cities across the country, accusing Chavez of forcing Radio Caracas Television International off the airwaves as a means of silencing his critics.

Chavez challenged the students to continue staging demonstrations, saying they won't weaken his socialist government. But he warned them against stirring up violence, suggesting authorities would break up protests that get out of control.

"Don't make a mistake with us. You'll get a firm response," Chavez said during a speech to his supporters at Venezuela's largest military fort.

Thousands of Chavez's backers gathered to listen to Chavez, who hailed the Feb. 4, 1992, military uprising against then-President Carlos Andres Perez as a justified rebellion seeking to topple a corrupt government that ignored the plight of Venezuela's poor.

More than 80 civilians and 17 soldiers were killed before troops loyal to the government quelled the coup attempt, which Chavez commemorates annually.