SANTIAGO (REUTERS) - Police clashed with student demonstrators in the streets of Chile's capital Santiago on Thursday, in the latest protest by university and high school students who say the government is moving too slowly on planned reforms.

During the march, which authorities had not authorised, students attempted to walk along the Alameda, Santiago's main artery, and demonstrate in front of La Moneda presidential palace.

But heavily armoured police officers dispersed the crowd with water cannon and tear gas, as protesters threw stones and set up flaming barricades.

"We occupied the street peacefully, but unfortunately the police pushed us back brutally," high school student union president Jose Corona, soaking wet from police water cannon, told local media.

The clashes are the latest in a number of high-profile protests in Chile in recent weeks, which have included a fatal arson attack and a scuffle with protesters inside La Moneda.

According to student unions, the protests are a response to what they perceive as a slow pace of reforms by the government of President Michelle Bachelet, particularly with regard to education.

"We the students have adopted a position of offence," Marta Matamala, head of the University of Santiago student union, said in broadcast comments.

"We are going to stay on the streets. From today onward, we expect that the protests will only intensify."

Bachelet, who began her second, non-consecutive presidential term in 2014, campaigned on a slew of reforms that included shaking up Chile's highly privatised education system and making university free of charge.

However, the planned reforms have been delayed and scaled back over the past year due to a recalcitrant Congress, far-reaching corruption scandals, and a sluggish economy, angering many on the left.