Police used water cannons to disperse hundreds of high school students who took to the streets Wednesday demanding that President Michelle Bachelet speed up promised reforms to Chile's dictatorship-era education law.

High school students declared a one-day national strike and marched toward an education ministry office but were repeatedly blocked by police. The marchers fought running battles with the officers, throwing rocks that damaged several vehicles.

An unspecified number of students were seen being detained by officers and put on police buses. Police did not immediately announce how many were taken into custody.

"These marches are a warning to the government," said Max Mellado, one of the leaders of the movement.

The strike appeared to have ample support Wednesday, but the protests were smaller and less organized than those in May and June that shook Bachelet's leftist government.

Those protests, joined by up to 700,000 students, ended only after Bachelet agreed to meet most of the students' demands, including eliminating a fee for a college entry exam for 167,000 students and providing school meals to 200,000.

CountryWatch: Chile

Bachelet also appointed an advisory panel with 72 members, including students, to review the education law created by the 1973-1990 dictatorship of Gen. Augusto Pinochet. The law transferred responsibility for education to municipalities, which critics say produces a deep gap in funding and education quality between rich and poor regions.

Students have grown impatient with what they consider slow progress toward changing the law. The panel "is good for nothing," Mellado said.

Bachelet was in Germany on an official visit Wednesday but Education Minister Yasna Provoste said the latest protests are unjustified since the government has done virtually everything it promised the students.

The students also demanded public apologies from authorities after police forcibly removed students who had taken over several schools in Santiago as part of their renewed protest movement.